Blueprint import/export should be a modded feature
If this means you open up your gui a lot more, sure.. but otherwise - hell no. Imo most of the blueprint strings look stupid anyway because they do everything with underground belts and beacons.
Weapons shouldn't lock on
This sounds like a rabbithole for modders.. but i actually enjoyed some of the top down shooters. On the other hand, it was really tricky for me to make towers that don't hit other buildings and it didn't even work for shotgun towers at all.
So i'm primarily worried about the friendly fire aspect of this feature.
Biters should be more aggressive, and probe your defenses
I personally do this too. it would simply be too expensive to build towers everywhere and i still spent 90% of my time to refill my (gun-) turrets, which made me deprecate the save game at some point.
It's also kinda fun to build your towers intelligently by observing where attacks usually happen.
Not to mention that you have more space to just leave your base with your car.
Clearing bases should not leave you safe
I thought they'd expand back into your artillery range anyway?
Seems like you're unhappy with the artillery, maybe remove it from the game? I'd just use it to constantly bombard choke points anyway and never really used it for it's original purpose.
Maybe the artillery(-shells) could also be a lot more expensive, as it's primarily a convenience tool to clear bases instead of doing it manually.
Alternatively, the whole pollution cloud mechanic could be removed, and replaced with a worldwide pollution count
Please don't do this. This would remove a lot of immersion and modding possibilities, aswell as making it impossible to make "green outposts".
Miners shouldn't output directly to belts
Consistence is so overrated. this would make building mining outposts 900% more complicated and soon literally everyone would use the "outpost planner" mod.
It also saves a lot of space ... and i really love how miners behave!
Boilers shouldn't have a water output
But why?!
That would make it ridiculously complicated to set up a row of boilers and i don't even want to know how my nuclear heat exchangers layout would end up looking.
The overlay even shows you where the water is attached and where the steam comes out.
"I understand that the current setup allows for some interesting layouts, but IMO it is not worth the usability cost."
Wtf? it's rather the other way around. Changing this would cost a ton of usability.
Pipes should work like electricity
No.
Electricity should work like Pipes
... Ok not really but you could add some Voltage and Amperage mechanics because the electricity network is one of the most boring things in this game.
Flow limits are great and it adds an immersive drop of complexity to nuclear power plants. Providing the water for your whole base through 1 single pipe is just lame.
Wow, the points by wheybags really fueled my anxiety that you're going to ruin the game..
Adventure mode
I downloaded [Z] Adventure and probably will do it again, but it was really buggy for me (not a single riddle worked) and all of the ruins looked super generic.
While i still think this is a good idea, there's a lot of polishing that needs to be made - like custom entities that are exclusive to ruins and some cool interactions with them, maybe there's a mall where suddenly a ton of biters come out? An really useful assembler/etc that's actually worth integrating into your base? (like whistle stop factories)
Radars
I don't really think forests should block the line of sight of radars, but the mountain part actually makes sense, but this might be hard to put into factorio as the whole map is really flat and a mountain might look out of place.
If there's something hidden in the forest it shouldn't appear on the map but if you zoom in manually you should be able to see it.
Bridges and tunnels
Bridges - yes (but put some love into it). Tunnels - tough one. I really like OpenTTD, but that game also has a non-planar world which makes tunnels actually make sense.
Caves: YES. This sounds like it would open up a lot of possibilities, maybe you could mine some rare materials under ground (like in Harvest Moon or Lego Rock Raiders), or find weird places and enemies (this might require quite some work from your graphics department.)
Robots should take up space and time
I agree, logistic bot factories are kinda stupid, I never used them except 1 time where i placed some temporary setup.
The construction speed when you have 50 construction robots in your inventory is actually very useful and satisfying, for the biter-base killing i actually wrote a small mod for myself that makes this impossible.
Items should have volume and mass
I don't think you can fix this. It makes no sense being able to transport 20k iron plates around either and it's somehow part of the factorio experience how it works now.
I actually wrote a mod that adresses part of this issue -
https://mods.factorio.com/mod/OverloadedTrains , maybe something similar might also work for the character (lower movement speed with many/heavy items in the inventory)
Power-user hotkeys
Okay... maybe? but don't entirely remove the ability to keybind this. Thanks for the hint that there's a hotkey for manual train driving, that sounds useful