Again this is really not true. Units regularly receive vet 4 and 5.
Well, you play mostly big team games, so I understand why you have this opinion. But in 1v1s (which I play most of the time), reaching vet4/5 never happens for vehicles and almost never for infantry other than Volks (and maybe Füsiliere, but I haven't used them for a long time). Also, there is nobody to build caches for you, so OKW still has fewer resources in 1v1s.
Obviously, the vet5 system is a problematic design decision, as it has different impacts in different game modes. IMO:
- either make vet5 superior to vet3 and achievable in every game mode but limit OKW in another way (like others mentioned: unlock the ability through extra tech, lock most units in tech buildings behind a separate unlock for each unit locked so you need a plan which units you will need in the match, or whatever you can think of)
- or give OKW vet3 with a comparable bonus to the other armies and give them caches if needed
Regarding Luchs: I haven't played as Brits yet so I don't know their exact timings, but US and Soviets can build AT-Guns, mines and/or handheld AT weapons before the Luchs hits the field (Soviets even without delaying their T70, which wins against the Luchs). Even in case it is OP, it is not as OP as people try to make it. Don't forget: OH has to fight light armor without light armor but with AT-Guns, mines and/or handheld AT weapons. So I don't see why allies will not be able to so.
But whatever, we'll see in the next few weeks, so everybody relax