Honest question, not trying to be rude: Why do people call them "utattemita"s instead of just "cover singers" or something like that? It's as weird to me as someone saying "Oh man, Ito Noizi is my favorite bijitsuka!", (although there are lots of people saying "mangaka" and "seiyuu" instead of "comic artist" and "voice actor"). I guess I answered my own question. People just like to use a Japanese word for no particular reason other than "it sounds cooler".
To add on as some food for thought:
It also happens in the reverse as well. Plenty of Japanese people like to use English words in their conversations as well. If you watched Utapuri, you'll notice that the ending song uses plenty of English. On the topic of Utapuri, I suggest you watch Freedel's version if you haven't yet since he pretty much reverses all the English into Japanese. It's hysterical. http://youtu.be/0Do_yMYrfmk
More food for thought:
Perhaps "utattemita" would be a more accurate term as well. The word "cover"
means that you sing the exact lyrics as the original. On the other hand, some utattemitas dub
songs as well which is different because the technical word for dub is to sing it in another language (ex. nano dubs songs in English). Perhaps utattemita is also used because it generalizes it more into one category "I sing"
Not suggesting I'm right but maybe something to think about.