I don't get the sorcerer

I'm fairly new, so I might be missing something, but to me it seems as if Sorcerer and Runemaster fill the same niche, both stylistically and mechanically, but the Runemaster just seems stronger.
Looking at builds online, they're generally around the same spells, too, so it seems they don't differ much in playstyle.

So does the Sorcerer to anything unique or is it just an older, less interesting Runemaster? And if so, have the developers acknowledged that as a problem and said anything about potential changes in the future?