While I’m glad that you realise that ideas need to be tested, adapted, and sometimes abandoned – something that the current devs don’t seem to understand – I do feel like this is another case of something I’ve observed before on this forum:
Normal people: If it ain’t broke, don’t fix it.
AoE2 fans: If it ain’t broke but it isn’t designed in exactly the way I would have designed it, make significant arbitrary changes until it is.
If you’re going to change the gameplay in some way, you need a gameplay-related reason to do it. I don’t see one in this thread.
I actually think the current archer line works well. One of the main reasons for having unit upgrades is to give the impression of technological advancement over time, and archer → crossbow → arbalest does that very well, probably better than any other unit line. It doesn’t matter if it’s not historically accurate or if some civilisations didn’t really use those specific weapons, because the game is (a) for a lay audience, and (b) an abstraction.