I replayed Spyro recently, and honestly, I felt like it didn't hold up. It felt like the objective was to get all of the gems, but there was no reward for getting gems. And maybe because it was a kids game, I just felt like it was way too easy. You could basically just walk to the end of each level, skip any gems and dragons that weren't in the main path to the exit of the level, and finish the game in a couple of hours. I also felt like the level design was kind of wonky. Like, there were paths where you would follow to a dead end just to get gems, and there was nothing else there. That's fine if that happens a couple of times in the game, but it was like this like 4 or 5 time per level.
Spyro 2 was a huge improvement to this formula, because you use the gems to buy upgrades and unlock new paths, or pay the dude to let you use the elevator and such. It made getting gems - and therefore the rest of the game - feel a lot less pointless.