Past versions of VL have had Evolution, and in fact 7.1 had it at points during the testing phase. The SlackBuild is present in our store, it's just that during the long period of repo restructuring, no one missed it. The build system is undergoing maintenance today. When that's done, a build of Evolution will probably be triggered to see where it stands.
You've been around long enough to know there's a package request forum. Also, are you complaining about slapt-get (or GSlapt) itself, or just that some packages you'd like aren't there?