And you're going to pick a Tiger-less Lightning War over Jaeger Infantry or Elite Troops doctrine because... ?
You don't see 250 because both the unit is individually useless on its own, and because other commanders are simply better and overshadowing the 250 commanders.
On commanders design:
Commander that buff infantry should not, also have access to super heavies.
Commanders with Super heavies should not, also have access to powerful off maps.
On 250:
The reason you do not see 250 is simply because the ability is too expensive, comes with infantry attached to it that you probably will need (even worse than assault Guards since the infantries are also available via stock) and because the 250 is simply inferior to any allied HT call-in. It has less utility while costing more to get, while nearly any Allied infatry has access to AT weapons. It is simply UP.
Other commanders are not simply better they vital, currently it really really hard to play Ostheer without specific commander abilities. Thus the have become what Soviet used to be, only worse since allot of these vital abilities are restricted to few commanders.