TL;DR
Move the filtering function of splitters to its own filter splitter tech.What ?
Add a new tech and new object to the game called filter splitter. It would function the same as previous splitters but the filter technology would be moved to a later technology more in line when when you get access to filter inserters and their cost more inline with the materials used in filter inserters. Also allow the new filter splitters to take inputs from the circuit network (because of course they should). All splitters would continue to be able to used as priority splitters.Why ?
There are a couple major advantages I see:- adding this tech calls to player attention that splitters can be configured (I suspect many players never discover that splitters have priority or filter functionality).
- some of the more complicated mod packs (like seablock) now have access to filtering much earlier then normal. In those mods filter inserters happen significantly later then normal splitters. I don't want to speak on behalf of those authors but this is probably not intended for what they created (not that they couldn't just mod in their own filter splitters). Breaking this up into two tech would probably be seen as a benefit.
The only real drawback that comes to mind is they likely won't be used often (much like how filter inserters are rarely used). The only place where I actually see large scale use of filter inserters if stack filter inserters in conjunction with circuit networks, but that is quite late into the game.
