I don't see any problem with it, it's weird that literally every game you start by building 2 houses before doing anything else. There are a couple civs with housing bonuses (Huns, Incas, Slavs) for different buildings. It's frustrating when you're running out of space to house your pop especially on Arena and BF.
a house takes 4 tiles space, cost 25 wood and provide 5 pop
a tc takes 16 tiles space, cost 275wood 100stone and provide 5pop
a castle takes 16 tile space, cost 650 stone and provide 20 pop
-the design that a tc which is 4x bigger than a house and more than 10x expensive (cost also stone), provide the same pop, must be for new player even more confusing than for some aoe player. (i know the tc have also more functions than a house)
-i dont think boom would be op, other civ got house bonus and not op. (huns, china, inca, slavs, dravidians...)
-i think also player who rush benefit. can add 2nd and 3rd tc with a lil bit more wood for farms or army
-maps with less space (nomad maps, bf, arena, socotra) are better playable and are not decided by not having space for making 20+ houses
-game focus in early stage more on micro and fights (still need 20+ houses to play 200 pop)
-9 vils start benefit for letting player decide where they build their houses
-less houses in walls. because bigger investment and wasting wood for houses. only palisade, will be easier to break in.
-start will be a bit different, player can do instant somthing else than build houses
-castle age will be a bit different 3-4 tc play give player 15-20 more pop
you say yourself that TC has more uses than pop space thus the price.
It wouldnt help rushes because the point of a rush is not builduing more TCs but army.
Why is it a purely good thing to focus more on army. aoe is not just a battle simulation.
No point in ever changing that.
... which is probably why the devs will implement this change.