I have a little anecdote on this subject. About a year ago I bought a copy of the first Sonic Advance, and I handed the game to my older brother at some point since he had never played it before either. As he was playing, he came upon a hazard or enemy of some sort at full speed and jumped over it. We joked about it and he said something like, "hey, it's almost as if I can react to the game."
Funnily enough, the Advance games seem to be at least a bit better (some of the time) at allowing players to react first time due to their level design and the inclusion of a wider screen, but balance this by largely removing the second chance mechanic with a larger amount of instant death pits.
One thing I have learned through discussions with the typical crowd that complains about running into stuff without warning is that they don't roll. Seriously: next time someone says that, ask them if they roll on slopes. 9/10, they will act like you're talking crazy. The amount of people who don't realize that you have the ability to go faster and bowl over nearly every enemy in your way by pressing down is staggering. Just look at footage any of these people playing the game. They never roll.
Rolling is powerful but it can be hard to trust it. I've been playing these games for an extremely long time and know them inside and out and still don't find myself rolling for safety, only when it's down a hill.
There’s a fair amount of enemies that, especially in Sonic 3, will hurt you if you just roll forward, such as the hermit crabs in Hydrocity. A lot of it isn’t just due to the enemies however, but how they’re placed within the level. It still takes memorisation and skill to avoid all of those.
