A lot of people have hit on the big issues with Mercy, so, I think I'll throw in my own thoughts on how Villain starting zone could have been fixed.
1. Move the starting zone to an altered St. Martial.
The reason for this would be to 'ease' players into the idea of being a villain. You're surrounded by glitzy bars, beautiful casinos, solicited by implied hookers, it looks like Arachnos runs the place more like another country than you'd expect and care about appearances, and it in general being a villain seems glamorous. The people you fight are bigger jerks or party-crashers, you rob banks, cheat the system, vandalize a few places, and steal some fancy stuff. The truly villainous things you do (and this one involves a revamp of longbow) is optional where you go to more slummy areas of St. Martial and find non-aggressive Longbow Volunteers. These are just dudes in t-shirts offering relief to refugees and their worst comment to the player is "please don't attack, we don't want trouble" or "would you care to join in and lend a hand, not too late." They're not even carrying guns. They fight your throwing rocks, brawl, and in rare instances will have a flare gun. Oh, and they're underling rank too so you don't even get a lot of EXP for fighting them. You just beat them up because you're a jerk and they possibly come across as holier than thou or remind you too much of Mormons or Jehova's Witness.
2. An inter-island highway system.
Pretty self-explanatory, just a road network between all the islands with St. Martial at the heart of it all so you find yourself going back.
3. mob diversity.
As mentioned, mob diversity is an issue, and sometimes even just making new, 1-15 level versions of existing mobs could do a lot, and in some place as fancy as St. Martial you could have stuff like casinos, resorts, bars, and restaurants owned by practically all the major groups.
Okay, that wasn't as big as I thought, but I could go on about my "wonderful idea" of revamping longbow but I think I wasted enough of folks' time talking there.