From Trekmovie.com:
"We are really passionate about Star Trek around here, you know, we take it seriously" said Orci, asked about the main reason behind this puzzling move. "We [Orci, Abrams, Lindelof, Kurtzman, AKA 'The Supreme Court'] know that this is quite a precedent, and that you can't just de-canonize stuff, you know, the stuff that's already on DVD, the stuff people paid for... But the thing is, the overall quality of the entire franchise is at stake here, its reputation is at stake, and these are not some irrelevant issues that you just ignore like that. So Alex [Kurtzman] and I brought this to CBS's and Paramount's attention, and they said 'what the hell, why not, make a list and bring it over, but be sure to start with Enterprise, cause that show is mostly crap', and we were, like 'Shit, we know, right?', but then the issue was 'which episodes do we erase from the 'space time continuum' [chuckles], and we decided to start with these two because they were just embarrassing, a disgrace not just for the studio, but for the fans as well. We'll be killing them more as we go, call it a 'spring cleanup' if you will, and this is about it for 2011. Since our Star Trek sequel is due next year, Alex, Damon, JJ and I think it would be only fitting if we 'killed' two TOS episodes, probably some time around April Fools day 2012."