This Bad snack goes along the lines of the saying " do not fix what isn't broken". Some designers like to change things from their original title that worked really well for no other reason then to change it. The feel of the game is very important to players. If a game was successful enough to merit the production of a sequel, then it probably had a lot working for it. When variables have been tweaked or mechanics have been removed the player will know.
Example: The change of the parry mechanic from dark souls 1 to dark souls 2
In the original dark souls game parrying an attack was keep to many popular play styles. It is a high risk high reward style that the first game got right. You could parry an attack based on where the opponents weapon was in his attack swing. If you pressed your button at the right time. your parry would go off and you could then attack for more damage. This mechanic changed in the second game. They changed when the player needed to hit their button in order to have a successful parry. The parry in the second game is less fluid then the first and therefore less effective. This bad design because it basically takes away a many play style that some players enjoyed about their original title.
There are many differences in new and old sonic games. Old sonic games are much better than the new ones, the physics in older version are better. The older game always created gameplay interesting and the player always enjoy the game in such a way that he/she concentrate on gameplay and felt themselves flying in the game.