What a cool bump (No sarcasm btw lol). To reiterate the point I made in 2014 the way Roman's debts are handled doesn't much sense. It would've been better if we physically had to pay them ourselves which would aleviate some of the uselessness of the in game economy.
Also as I'm up to this part in my current save I always thought Broker and Hove Beach in particular should've been a no go zone after Dimitri's betrayal. Niko says that he and Roman had to get away for a few days so I don't get why he'd go back so soon. Going into Broker/Hove Beach should've resulted in Dimitri's men becoming hostile like cars going after Niko every now and then.
Being able to pay off Roman's debts for him would have been interesting, and maybe as a way for Roman to do favors for you for helping him out (though I can't think of what he'd offer other than the standard free cab rides, or paying for meals when you take him out).
Hove Beach becoming a no-go zone would have made sense, it kind of reminds me of what happens to Portland in GTA III. Pretty much every gang there hates you and tries to kill you on sight. Though I think III's was a bit overkill and became too annoying (especially in St. Marks with the mafia guys' shotguns). Maybe in IV, you could have gotten a warning by any Russian gang members who spot you to leave before they attack you, kind of like how they warn you to leave if you bump into them. And maybe after the story ended, once Dimitri is dead (and Bulgarin along with all of their heroin being destroyed, as we'd find out in BOGT), Hove Beach would be safe to visit again due to the Russian mob probably being in shambles by that point.