I think people have looked at the original Resident Evil 3 through rose coloured glasses and forgotten that it was a game made at the figurative last minute. (Incidentally, for those who want to know, the original idea for the game expanded and expanded until it surpassed the PSX's hardware, necessitating it to move to the PS2. Where it would become Devil May Cry.)
But the original Resident Evil 3 was a mess of games being developed and cancelled, especially as at the time, Capcom was planning 3 major releases on the consoles at the time; Resident Evil 0 on the N64, Code Veronica on the Dreamcast and a Biohazard 3 for the PS2 (which was cancelled because it would take too long develop and the game they were then working on was cancelled). Nemesis ended up being a game that was thrown together while work was being done on Code Veronica. How thrown together was it? Well, Jill Valentine was only used in Nemesis because she was originally going to be the protagonist for CV, except the writers were forced to use Claire because of a line from RE2. Though this ended up allowing the PSX team to use Jill for Nemesis.
Nemesis was tacked together, hence why it used a lot of the assets from RE2 and why it was modelled on Japanese cities rather than American ones.
But back to the original point, its hard to build upon a game that was so short in itself without making something else entirely. Could the remake have done things differently or kept some things in? Yeah, of course. As much as I hated Gravedigger in the original, I kinda wish we got to see what they could have done with the current era of technology. Though I suspect we'll see it in some story dlc featuring Tyrell or perhaps even Mikhail before he was injured.
I'll be discussing the remake in more depth in an upcoming podcast I do with a couple of friends, about various Resident Evil games.