Eric is the soul of this game. He's absolutely essential, no cap.
I remember my first playthrough of vanilla BB, going in blind with no walkthroughs. I literally couldn't beat Eric in time. That's what made me desperately scour the internet for guides just to find a way to deal with him.
Tbh, without Eric, BB would just be another mediocre RPG/VN on the long list of games I've played and forgotten. It wouldn't stand out at all.
Even in other BB-based games/mods where they make Eric a total pushover, I find them boring af. The gameplay loop is just... plant some cams, wait for your bank account to go up, buy stuff, and then just repeat the same interactions with the girls day in and day out to progress the story... it's a total snooze-fest.
You can cut a lot of the NTR content, but you HAVE to have Eric. For example, make it a "game over" if you don't defeat him. Of course, that's a bit too harsh. Maybe you could give Eric a schedule, and if you don't hit certain objectives by a specific time, he'll NTR certain girls—I think that was the original design.
But I gotta say, even in the vanilla game, after I finally kicked Eric out, I felt this huge void. I guess that's just what BB is. Eric is to this game what Iudex Gundyr is to Dark Souls 3—a tough-as-nails boss, but the satisfaction you get from finally beating him after all that struggle is just IMMENSE.
I’d rather recommend keeping Eric in there like in the vanilla BB, then split the story into several chapters. Every chapter would have a boss-type dude like Eric trying to corrupt the girls, with different targets each time—say, the male classmate Lisa mentioned at the start, or the bar owner Alice knows. They’d fit in super naturally as main villains. So the whole game turns into: beat the enemy or get NTR’d. Kinda hype just thinking about it.