Let's be real for a second. Before S11, the only reasons to visit Mercury, Io, Titan, etc was for a small handful of story missions along with the occasional quest step or bounty here and there, if that. After that, they were pretty pointless. Getting rid of old, outdated content to make room for the new stuff is a natural part of developing an evolving game. World of Warcraft does it as well. You're gonna be okay.