Try making it actually feel villainous. Red-side always seemed like little more than a slightly shady version of blue-side. If I'm going to be playing evil, man, I want to be f*ckin' EVIL.
Here's the thing. There are two types of villains. Those who want to avoid capture and must sneak around, blending in with the rest of society and those that aren't terribly concerned about capture because they can either escape the clutches of the law easily, or outgun them.
Honestly, redside wasn't evil at all. It was like an anti-world. Not the opposite of blue side, and not really run down, just creepy. More scary than evil. There's a difference, in my mind. To me, redside should have been like blue side, only more run down. Perhaps parts of it were, but with all the snakes and spiders I was distracted. What spiders and snakes have to do with criminal types is beyond me. I never did like that arachnos storyline thing. Spiders. Yick!
A real limiting facet of redside was that there was no room for the white collar criminal. No way to pass a bogus check or scam old ladies for their SS checks. Not sure how much fun that would be anyway, passing a check here and then moving around quickly so the boys in blue can't come get you. I suppose they could have written that into a storyline somehow. (For all I know, they did. I only did the content that gave my blue side character a badge)
I guess, to be on point, the first thing I'd do is lose Lord Recluse. Or keep him and take those stupid spider-legs. Lose the rest of the spiders and snakes. Keep the human npcs - family, sky raiders, freaks, etc. Change the architecture somewhat. Have actual neighborhoods with suburban subdivisions that have single family homes. Just like Spider-man had bills and romance issues to contend with, criminals can sometimes have wives and children. They don't all sleep in apartments. Most criminals are regular people, only desperate, but instead of it being due to bad economics, it's usually due to poor decisions - like getting incredibly high interest rates on their student loans. And instead of just not paying the darn payments, they rob a bank - when they'd probably have gotten away with more money, less risk by just not sending them any money.
Forgive me, I'm sleepy. I might need to channel that into an actual story...