I don't hate NTR with a passion, but I do dislike it overall, maybe because my first experience with it was Thug Hero Party.
The problem with NTR haters is that they stretch the definition too much. If the protag is the owner of a brothel and has girls servicing customers, that is not NTR because the protag and the girls are not in a "Loving relationship". It's only NTR if 2 characters have a loving relationship (lovers/family etc).
I'd have to agree to what was said before, lots of games where NTR is avoidable have very little non-NTR content or even none at all and what is there is bland and boring. And as long as NTR as I've described it is avoidable I will play the game, and if the NTR is avoidable I'll even play through the NTR scenes in a gallery or on a fast second playthrough as in my head I can see it as an "what if" scenario and disconnect from it emotionally. That's also what a lot of NTR lovers don't think of or don't understand, the reason some people dislike or hate Netorare specifically is because the story is aimed at emotionally hurting the reader, who identifies or at least perceives the story through the protagonist, rather then just showing the act of cheating. Some NTR lovers advise to imagine yourself as the other party, identify with the character who is stealing the protagonist's girl, but that is not how Netorare story is structured and told, the writer want's you to relate with the protagonist and suffer with the protagonist, so if you enjoy netorare by imagining you as the one doing the stealing, you're doing it wrong, and what you really want is netori.
Sorry for the long rant if it turns out to be useless.
As for a interesting scene I think will please both sides, and surely will please me, here me out: The protagonist needs to sex train a new girl for the job but he doesn't just use his own body to teach her, instead he gets some other guy to be a test dummy, maybe a male friend of the protagonist, and tells the new girl what and how to do and how to behave to better please clients. Basically the protag is still in control at all times even if he is not the one doing the fucking, so all but the NTR-hating purists will be able to enjoy such a scene.
Hope any of my ranting was of any use at all. And:
Edit: Just noticed the last post and wanted to answer your question about main girls in non-ntr things. Depends what kinda things you thinking about! You can have the main girls do bartending, gather info about clients from the prostitutes , maybe even be a bouncer if their character allows it. For my taste I'd even allow them to do striptease for the clients as long as it's "Look only" but I can see lotsa people wouldn't want that. Maybe one of them is a sort of emotional relieve for the prostitutes , you know the sort of girl that can help and support them emotionally and such. Basically anything that doesn't involve the main girls touching other men/clients is free real estate IMHO.