Would that not feed into the power creep that you are usually complaining about?
Allied factions got buffed, OST fell behind, OST T4 got buffed, now you suggest moving it to T3 which might cause Allied buffs again to counter the earlier spike etc etc.
I did not suggest it should be move to T3 building but to BP3.
As for power creep it seem the MOD team is determined to keep having it.
I think the upgrade at the moment is in a good position. OST has an amazing T3 line up and is absolutely on par to other factions by the time T3 comes out. They lacked a bit in the late game, which was countered by buffs to their late game tier. No need to buff the mid game though, at least from my experience (to be fair though I have not found the time for excessive CoH2 sessions, but I think I still got a decent impression of how OST works now)
The moving into BP instead of a building increases flexibility a lot, currently Ostheer are almost forced to build all buildings if not using a commander unlike other faction.