Oh I hate the title! I actually wrote for Pastry Box about it, no clue if it will see the light of day though.
My thinking is that it is a catch-all, and as someone who used to be known as a webmaster, I know all about catch-all job titles. UX Designer, and especially UX/UI Designer, job ads require you to read exactly what they are advertising for. Do you really need to be a wiz in CSS/HTML? Do you really need to have your portfolio on Dribbble? What is interesting is the process surely, and not the fidelity of the end result. If that's the case then surely a Visual Designer, or a Front-End Developer is needed.
I really hope that this catch-all splits into the various terms it warrants.