Erm, I don't see what's so bad about that prank. More than that, I don't see where it's insulting.
Frankly, I think it's rather stupid to not read the manual at all. It's understandable that you may miss something that's written in there but you should at least try.
Myself, I like this part
:
"So MSI decided to ban people from support, RMA and the forum who has done the damage themselves or didn't read the manual the first of next month.
We know who you are, and we have gathered enough information via our RTFM-chip."