Isn;t the original still good enough?
This one has sharper visuals, 4K Texture Uplift, DLSS/FSR Support, smoother gameplay, and faster load times.
I guess it doesn't matter much for PC version but now it's released for the modern consoles too: PlayStation 5, Xbox Series X/S and Nintendo Switch 2.

What about Sega DLCs for it?
https://www.youtube.com/watch?v=1xYfx3XObLg
Nope. They're not adding that.