Even with its camera problems this is still the best Sonic game ever made, hands down, the movies may be far from perfect but they were right to use it as the main inspiration for Sonic 3.
Base +22, do_it_again_chen +15, weezerbuddyholly +4, dlvja6490 +6, Mr.pickles25 +6
The gem collecting missions were to further break up the pacing, and encourage players to get used to looking around the environment for doodads and secrets. There's an awful lot of content in the other two kinds of levels if you take the obvious paths (which amount to "run really fast through the level" and "blow everything up in the level"). Similar to why God of War has basic puzzles; you're not playing the game for them, they're just there to give you a break between action set pieces.