Well, I’m using it for a non-trivial (~50k SLOC) cross-project in-beta product, so it’s certainly not “nobody”. I committed to Scala-IDE back when IntelliJ just plain wasn’t working for Scala.js, and haven’t yet felt much need to switch.
I wouldn’t say that it’s perfect, but it’s certainly not as bad as you’re making it out to be, so long as you understand the workflow. It has only one bug that really annoys me, which is a tendency to forget about my most recent changes. (I don’t yet know whether this is mainly a Scala-IDE bug or an Eclipse one.) It does require picking up the discipline of re-eclipsing when I make dependency changes, which is disappointing in principle but not really much hassle in practice – it’s just something else to do along with reloading my sbt file.
And mind, I’m not saying that we should point newcomers at Scala-IDE as it currently is – the experience is still too rough. And I don’t know if it’s ever going to provide the truly seamless Visual Studio experience. I’m saying that it would be lovely if we could put some more resources behind Scala-IDE to get it to the point of being comfortable for Eclipse-experienced newbies. From what I can see (mind, I use it all day, every day) that doesn’t seem like an unreasonably difficult project…