Why is the name controversial?
Many astronomers and scientists have been vocal about saying the moniker is, more or less, stupid, even though the term has fully entered the lexicon at this point. There are even pop songs named after the event.
The complaint is that "super" is hyperbolic. The moon is larger and brighter at perigee-syzygy (the technical term), but, as noted by NASA, "a 14% increase in the apparent size of something that can be covered with a fingernail on an outstretched arm won’t seem significantly bigger."
"Super," detractors contend, is a strong description for something that's just a little enhanced. If Superman were super by this standard, he'd probably be more accurately dubbed Above Average-Man.
Nevertheless, a supermoon is larger and brighter, and it's worth enjoying any space event that reminds us to look up and think about the enormity of the universe. So, don't get too worked up over the name. If you enjoy seeing the moon at its largest and brightest, it's a damn good occasion to be outside, looking up at the night sky.