The changes for Panzergrenadiers hardly had anything to do with the opposition they faced, clearly demonstrated by the fact that their new timing is only 1-2 minutes faster than what it used to be which barely makes a difference in enemy veterancy or weapon upgrades, and much more with the fact that they were incredibly hard to fit into builds when they were available at a time where most players would rather / had to invest in light vehicles or an ATG.
Think you underestimate the importance of timing.
Pg (and Ober) used to have the role of "elite" infatry and come in most cases after one already had the main core of his army built. Pg where meant to be a supplement to they army and not its core.
Even is one tried to rush T2 Pg could not really take back the ground lost while waiting for BP1 and T2 structure.
Currently having Pg as core infatry (with AsG and Ostrup)is allot more common.
PG timing was fine for years, they slowly power creeped to become UP.