I think you are right about Star Fox, Crash Bandicoot, Spyro and Sonic.
But the other franchises are too short (Conker) or they are not all the same franchise (DK platformer, DKonga, DK: King of Swing) so you can't say that they have gone sour. Maybe the next Conker will be great and maybe Nintendo is going to announce New Donkey Kong Country for the Wii and those franchises will be beloved again.







