The guys WCW were pushing were older for the most part trying to compete against new stars that WWF made. And like someone said before, at that time there was much more to lose so sitting on the same shyt wasn't smart for business. If TNA was close with WWE in ratings every week, you'd probably see Bryan pushed tough due to the fan reaction. It doesn't matter if these new guys leave WWE cause Vince knows they can't blow up anywhere else. If Bryan went to TNA people would watch a bit but TNA still couldn't compete with the machine. When you put a stranglehold on the entire industry you can pretty much do what you want.
1) Age isn't really relevant. If fans are still buying tickets and merchandise, PPVs and going to house shows
2) Actually it was smart for business, cause they drew money. They only stopped drawing money because their angles were terrible and booking got dumb, and WWE was putting on a better product. Not cause Hogan, Sting, Nash, Goldberg, Flair, Hart were on top. Aside from Jericho, the guys fans were begging WCW to push (Guerrero, Benoit, Malenko, Saturn) wouldn't have stood a chance against The Rock, Austin's, Foley, Vince Mcmahon, Undertaker, DX, etc...they didn't have the charisma, the promos skills, etc to stand up to the Attitude era guys.. (Eddy developed those skills in WWE, he was great in WCW, don't get me wrong. But as a upper mid carder. Not a maineventer)
3) I do agree with your last two points though