I agree.
As a new pilot who trained in the 152, I think it was a good basic aircraft for the purpose of training. The problem is the newest ones are about 20 years old, so even the good ones are getting tired.
Cessna is going to come out with the new sport pilot rated trainer which looks like a pretty good product, but it's not a full-blown license trainer.
There are other aircraft (like the Diamond Katana or Slingsby Firefly) that are good new-generation training aircraft, but I don't think they have too much more to offer over the good-ol 152.
They might be more fuel-efficient which makes the operating cost better for the school, but when you're just droning along doing circuits, stalls/spins, emergancy procedures and the occasional cross-country I think fuel costs aren't that important.
I'll ask some people the next time I'm at Cessna (I go down to the Wichita plant fairly often), but I bet the answer is that product liability is what killed them in the 1980's and even though the nostalgia of starting up the old line is interesting, it would not be cost-effective to start up again. Their money is better spent making millions on business jets.