IMHO it is far more important to teach recognition of and control at slow airspeeds than doing loads of spins, and learning to recognise and break the chain that could lead to a stall/spin (poor vis, distraction on a glide approach etc) because lets face it, it's not going to happen unless a lot of other things have already gone wrong. We encourage people to go for a spin in the aerobat with our aerobatic instructor as part of an aerobatic sequence, but they don't have to if they don't want to. Many students and instructors simply don't have the stomach for it.
As for the Tomahawk, well if you haven't spun one then I guess you'll never know! The problem there is often people do a half hearted recovery, which will work well enough in a 152, but the Tomahawk requires the recovery to be effected properly.
Sadly in my years in the industry, the only people I have known who have spun their way to kingdom come have been commercial pilots showing off with idiotic manouvres like a low pass and steep pull up, who should have known better.
slim-slag says:
"I've never spun one, never will (intentionally), but I hear the tail twists and turns quite spectacularly during the maneuver. Have you taken a look behind you, is it as hairy as they say?"
Ah yes the old tail wobbling story. It's an old wives tale. Next time you shut an aircraft down, listen to the airframe shudder. That's what happens in a spin, and not just to Tomahawks! As for certification, well read the POH.