Yes, I'm aware of that...it was done on purpose.
This limit is in a lot of other places - stateblock code, drawprim code.
Have you checked that it will all interact properly using this higher limit?
Specifically, have you tested a sampler > 4 with SetTexture()?

I think this problem should be solved by a single patch that updates all the necessary places to use the higher texture units value, as opposed to the legacy one (there's some caps code to write for this).