First, I would like to point out that they are not new. *Cap'n Obvious*
The difference is most likely that they are not Super Sneakers*Cap'n obvious again*, but Soap Shoes, which let him grind in Sonic Adventure 2, which was there purpose in real life as well. More or less it was just "shoe" horning a product into the game to increase sales. ( You can check the SA2 trailer and alpha/demo and notice Sonic had his normal shoes in there as well)
Nowadays, Sonic can just grind with his Super Sneakers.