Hey ssilk, sounds like I misunderstood your comment, I apologize for that.
I don't agree with your reply about bottlenecks still though:
Of course you do: Before and after your upgraded area.

You can of course upgrade everything, but ...
Let me explain. when your factories (eg furnaces) are fed by or put their output on level 1 belts, upgrading to level 2 will always result in the same or more throughput. Ie. it's no worse, it's always the same or better because what the previous belts could carry is handled by the new belts and then some. I know there is a "change in speed" between the two belt types but the throughput doesn't decrease. Remember there is also buffer in the factory itself.
Your point about the factories and not matching ratios makes sense and that would be a bottleneck, but a non-issue to me in most cases because the throughput will be the same or better. Ie. if one of the factories is upgraded in a chain and now it sits idle for a bit of time while the resources are inserted isn't a concern to me because i'm producing at least as fast as before or faster (given inserter speed, resources provided and needed etc).
I think our points of view are clear to me now. I care about throughput and not bottlenecks in most situations. Ie. I used to care about ratios but realized it really doesn't matter that much as long as I'm producing at a reasonable rate or fill the resources (belts or logistics network).
What I want to say: It's not clear or proven, that upgrading anything is always better. Cause you need more raw material for that. For example. In the time you produce upgraded items to automatically replace stuff, I would probably be much faster with a strategy of not updating.
Regarding the above, I see you point, sometimes if you consider resource cost it might not be proven that upgrading is better, but only if you consider resource cost as well, which may or may not be a factor for any particular scenario. This is why I suggest that it's a configurable feature. Also it's a game, it's not all about resource costs sometimes I just want to have the fastest everything in a factory because I can/have the resource. This also gives other benefits such as more module slots in factories, furnaces, faster belts feeding more factories without running dry on resources for any factory.
Your suggestion leaves new players in the doubt, that it is always better to update. The truth is, that it is not always the best way. That's what I'm against.
I don't think it leaves any new players in doubt. The entire game is about building and automation and resource management. A new play can easily spend all their resource making 10000 belts at the beginning. The entire game is a learning process and open to interpretation/opinions. The feature can be defaulted to off for new players but should be available to be enabled if desired just like the pollution display default which I always disable so I can actually see the minimap. I would argue this default is not the best for new players. When their minimap turns red and they wonder why they can't see their factory.
Also consider this: By upgrading to the best factory/belt, the player doesn't need to carry around 3 other types of belts, 5 other factories etc as they go and upgrade certain factories manually, it also makes managing the factory easier, you always know that the speed of every factory is constant, every belt constant and the ratio math is easier. I admit these depend on playing style, and hence why I think it should be configurable.
I didn't say that. I said: Keep it as they are and build new ones at other places, cause it is in most cases easier/cheaper.
I'm not sure how this is different than my interpretation. It still sounds like you are saying to build new factories instead of upgrade existing ones. Sorry if I'm not understanding you properly.
For the stuff I already built I do in some, no, many cases. Why should I change it, if it is working?
Factorio drags the player very strongly to optimize. You always want to optimize in Factorio.

Everything, everytime. But nobody - only the player - forces this. So what I say is basically: Instead of optimizing you should consider also a play-style, that just builds something anywhere else.
In many cases this is not possible, cause - for example - the player has built fantastic complicated stuff, that is not possible to extend. Yes, in that cases it is much better to upgrade. But don't say it's always needed.
One reason you might want to change it is to get more throughput. Eg. if you manufacture common components like gears or copper wire in a central location and ship it on a bus or use robots, you will likely want to increase the speed of manufacture for those goods as they are needed more later (this game basically has exponential growth of resources as you develop more complex items).
I never said you always need to upgrade. I said I want a feature that upgrades everything you tell it to based on the behaviour I laid out earlier and I also clearly said it should be configurable. Sometimes I might want it on, other times not.
That is one way to do it. There are others, like building more, not faster. Another is for example to rush to logistic bots. Or build a railway, so that you smelt the stuff on the outpost directly. There are also the big theme of modules. There's a lot of other ways to bring your factory to run faster than just upgrading entities to the next stage.
What I mean is, that a beginner doesn't know that all and it should be kept as his own decision.
I agree, and I never said that upgrading is the only way. I also said it should be configurable
In any case I personally would really like this feature but the current upgrade mod being integrated into the game is much more important because I can just drag areas around my factory selectively and get it upgraded removing much of the work.
Please keep in mind that this feature would be useful to some and not to others based on their playing style, scenario, type of playthrough they are doing and (as I mentioned many times) should be configurable. I also think that it should be fairly easy to implement because almost all of the key/hard components are already there. These are in place upgrades for most buildings/belts etc. construction robots building and replacing entities (stock game and also upgrade mod), logistics network which tracks totals for each items and max limit on each item though highest smart inserter limit. All that is left is to pick a random entity (or the one that was first built) it really doesn't matter and upgrade it when the limit is reached.
I really feel this would add value to the game for hopefully very little development time. Just think how nice it would be if you just want to upgrade all your walls, gates or turrets in your entire factory for example (some require mods to add improved walls etc) and you just tell your robots what to upgrade and you don't have to worry about it. Think how nice it would be for this to happen without draining your entire surplus of walls and turrets because it only does it one at a time when you have reached the limit you requested while you are busy expanding the factory, etc.
