Hear me out, and I'm gonna use Sonic as an example here;
Sonic Adventure is an old ass game. The people who worked on it aren't with the company anymore.
New Sonic games are all lacking that spark, relying too much on automation and boost.
A Sonic Adventure Remake could fix future Sonic games by tasking the current DevTeam with faithfully recreating the original. They would learn why certain things were made the way they were, why stages were designed the way they were and would get a feel for how the different characters should move in the environment.
Then, the devteam can take what they learned from the remake and apply it to a brand new Sonic game.
There is value in remakes, as long as they're done properly and not just as a quick nostalgia colored cash grab.