No... Heroes 4 isn't "G" or an "absolutely different game." There are simply more differences and innovations between Heroes 3 and Heroes 4 than between Heroes 3 and Heroes 2, and so on...
Note that I didn't say that about Heroes 4; these are quotes from forum users (I don't remember who exactly), and I specifically asked to pose that question to Kenny...
The explanation is solid and good, but wasn't there youth at that time for whom it was too early for "girls, beer, and the like"?