Not too long ago I submitted a ticket to WIS saying I wasn't able to select combo practice for my punter at a DIII team I had picked up. The response was that the option had been disabled because it wasn't working "as intended". I'm not sure what that exactly meant. And I don't recall there having been an announcement about the change, but maybe I missed it. Also, the response didn't specifically say whether or not practicing kicking for the punter (or vice versa) worked "as intended" at the DII level and above and still had an impact.
The interesting thing is that if you have been a coach at a DIII team since before this (unannounced?) change, you can still select combo practice for your punter/kicker. I know because up until this season when I switched to another rebuild project, I was in that position. I can't say for certain whether or not it provided a benefit, but I never saw a drop-off in the performance of my punters.