Speaking for myself, I actually prefer the way this second map has played out, in terms of Runecraft allowing everyone to be more spread out. One of the things I know I'd constantly worry about if I was set up close to someone else is whether or not I was infringing on stuff they were planning on doing later, or taking resources that would more rightly belong to them, or so on. That probably sounds weird to a lot of you, but it's the way my brain is wired. I'm also kind of a control freak in that I like everything being where I left it, so if people start building too close to where I think I might do something later, I start to get twitchy. Even on gargamel, where there was no one really super-close to me, I worried a bit about that sort of thing happening. That's the main reason I went with an island on this map: there are nice natural boundaries, and I know I can do whatever I want on it without stepping on anyone else's toes. I have nothing at all against working with other people on a group project, because that can be a lot of fun, but I want my own personal area to be a good way from anyone else.
About the new biome system, I certainly appreciate that Jeb and company are still putting a whole ton of effort into updating and expanding the game...but I can't help but feel something like "Enough is enough!" about certain aspects of it. Like AA said, there's almost this sense that everything you've worked on previously is deprecated by some of these major changes, that you're essentially being forced into a reset. Case in point: I've essentially been working on a single SP map since when I started playing the game in the 1.8 beta days. I have something like a 3000x3000 meter area of the world explored (basically a 3x3 grid of the original map item zoom level). There are already some funky boundaries around the center square of my world, because I'd only explored about one map's worth of it when the initial biome generation change happened, but I can deal with those. With this new change, though, I've pretty much given up on exploring out any further, since it'll introduce a whole new mess of boundaries, and whatever I create will be thousands of meters away from spawn anyway. Sure, the new launcher finally makes downloading and maintaining old versions easy in an official sense, so I could just do that, but I can't help but wonder why I'd have to in the first place. I understood the initial biome change, since the game was still in beta, but now we're (at least nominally) playing the "released" form of Minecraft. Resetting the entire system yet again feels really drastic.
But yeah, it's no secret that I work at a glacial pace, so the last thing I'd want to see is another full wipe of the map...hell, I never even finished some of the stuff I wanted to try on gargamel. The thing with me is that I tend to like "living" in a Minecraft world a lot more than building something huge and crazy: I have a lot more fun with exploring, or caving, or farming, or just tinkering around with stuff. My fortress is the first really big-scale thing I've tried, and I do want to get it to some semblance of finished, but I know it's gonna be a while before that happens.