Their fall coincided with the rise in popularity of FPS.
I think its more the case of people just got bored of them . The market was simply flooded with them inthe 8 and 16 bit days, even a film licence would even up being a bog standard Platform game.
Point and Click games have had their day, so have Flight Sims, VS Fighters Japanese RPG's, and Racers have all seen a decline. Its not all down to FPS, its also down to people tastes have changed and a lot of people have simply got bored of those genre's, and in a lot of cases developers just can't cut it anymore.
The same will happen to FPS's , people have already tired of WWII based FPS. They'll tire of HALO and COD when they're milked to hell and back.
Half-Life is better than anything Sonic Team has done since the Mega Drive. There, I said it
I take it that was meant as an tongue in cheek . Its not really fair to compare HALF-Life to ST games, but I will say PSO was every bit as good and polished as any Value game and that as magical gaming experience.
I also think Samba De Amigo is one of the greatest games ever made, and a game that never fails to put a smile on my face.