The training system problems where 2: People hated they ahd to choose to buy either trainings or charaters, and that it felt stale after a while, both could been solved without this thing pretty bad system. Every game wit builds that are not RNG (either you have all perks from the start or you buy stuff over time like a MOBA) keeps things fresh with constant balance changes, new items/perks and some reworks here and there. The team in beta was clearly not too much into the balancing for obvious and valid reasons doing os just some tweaks every now and then, that's why it felt stale, that's it.

The other problem...I mean, just make people have all the trainings for free from the start, or maybe make a small ammount of them unlockable with early missions and add new awekenings every season in the FREE part of the battlepass)not further then the midpoint better) so peoaple have to grind a bit too and are engaged longer.

Everyone defending the system only brings the staleness problem while a lot of popular games do not have RNG builds in it, they just balance regularly and add content often, easy as that.