..is it simply because the writers need a pantsy, and pull him out of the villain pool the same way they constantly do with the Rhino, Mr. Hyde, the Wrecker, the Shocker, and others?
Thor is dead---he hasn't progressed. Cap is dead--he hasn't progressed. Spider Woman has become a weepy, hand-wringing mess--this is progression? Spider Man's web has become so tangled no one really knows what the hell is going on with the character anymore, and fewer even care. Monica Rambeau/Pulsar has gone from an intelligent, disciplined, emotionaly-mature adult woman to a nasty black urban stereotype who spouts idiotic remarks. That's progress to you? Daredevil has been completely flummoxed by life itself (ah, the horror, the horror) for years now.
And I could go on about the number of 'classic' (or near-classic, at the very least, established) characters that have become utter bores or have been badly mishandled by amatuers: including Gambit, for instance, Machine Man, and Storm (thankfully, Carey and Brubaker have done wonders recently for Polaris, Rogue, and Mystique, and to a lesser degree, to Ice Man, Havok, and Cable).
IM has become a monster and almost a god in terms of power, and is thus no longer interesting, at least to me.
Reed and Hank Pym let many of us down during CW--is that character progression? Maybe to you, it is. To me, it's just laziness on the parts of the writers, which alter these classic character's personalities to fit their stilted storylines. But Pym's a whack-job, so what does it matter what's done with or to him--Right?
The Grey Gargoyle is no slouch---he has a very deadly power, and one he can easily use on enemies. IF he has'nt devloped in the manner in which you suggest, it's because....
....dragging him in and out of books in a few panels to get a story going is no way to show respect for such a character.
Leap Frog I can see being used this way, and perhaps the Gibbon or the Grizzly, or even the Vulture in a worse-case scenario, but not the GG, not Electro, not the Living Laser, Avalanche, Spiral, Vertigo, the Cobra, the Unicorn, or characters of that caliber.