I agree. I've always thought of ways they could have made RE5 better, especially based on those early trailers that made it look like a single player experience and had tons of enemies on screen with mechanics and animations that were never in the final game. It seemed like a natural evolution and a more effective version of the horror by swarm idea introduced in RE4.
A hypothetical remake could potentially do this type of horror more effectively since modern consoles should be able to handle lots of enemies on screen at once. Not to mention, enemies could also be a lot more formidable if they completely revamp the enemy A.I. like they did with zombies in RE2, so that enemies don't just run up to you and stop so you can shoot them.
The thing with Resident Evil 5 as well is that I thought it actually had its moments in terms of horror. The Chainsaw Majini for example completely sh*ts on Salvador from RE4. He's a lot more stronger and can take a shotgun blast without falling to the ground to get knifed, and sometimes, he gets back up from death and becomes more erratic. There's even a section where you're forced to split up from your partner to open a door and one of them corners you. Then there's the instakill Reapers who give you limited time to attack and just keep forcing you back while also blinding you. I also thought Lickers were done really effectively here too.
I know Resident Evil 5 is an action game, but I don't think people give it nearly as much credit as it deserves for how it uses horror, especially when so many people still pretend RE4 was a survival horror game. But Capcom has once said that they did genuinely think they were making a horror game with RE5 because they were obviously high on RE4, but a remake could definitely rectify that by giving in to its more survival horror sensibilities.
I also think they could have made the on-rails sections more engaging, which is something RE6 actually did. For example, instead of both characters shooting at the Majini on motorcycles and vehicles, only one should be on the mounted gun and the other driving. The Ndesu fight could have been done on foot with both players needing to scramble so one could distract him while the other shoots his weak point. The lack of engagement in those sections just completely removes any ounce of tension that could have been there by simply giving control to the player and that's the exact potential I see in a remake.
You also mentioned having the game take place at night which I don't think is completely necessary because I think there's an interesting juxtaposition in having a survival horror game set in a hot and sunny setting like Africa with its beautiful vistas and wildlife. Which btw, the lack of wildlife and infected animals is something I've always wanted to see as well. But, I'm kicking myself because you actually reminded me of a shot in one of the trailers that I cannot for the life of me find right now. It had Chris walking in an outdoors setting at night that looked like it could have potentially been the location where you fight the Ndesu, but it struck me as interesting because you can't walk freely in that environment and somehow that shot made it into one of the trailers and is actually what always made me wish we could have fought the Ndesu on foot.
