I know what really bugs me about the foofaraw over Twilight becoming an alicorn princess: the idea that it will "undermine" the show's principles. People are worried that Twilight's going to ascend to princesshood, suddenly vastly outrank her friends in both status and power, and leave the whole "friendship" aspect of the show in the dust.
But "My Little Pony: Friendship is Magic" is about solving friendship problems. Problems like, what if you don't have enough tickets to a fun event for everyone (The Ticket Master)? Or what if your friend has different standards of cleanliness than you do (Look Before You Sleep)?
So if Twilight does level up beyond her friends... well hey, that sounds like a FRIENDSHIP PROBLEM to me! It might lead to conflict between the newly-crowned Princess Twilight and her friends, and she'll have to figure out a way to deal with the situation. In other words, the same sort of stuff MLP:FiM has been about since day one!
And this is apparently going to happen in the season finale, "Magical Mystery Cure", written by Mitch "M.A." Larson. Remember him? He wrote some of the show's most awesome episodes: "Swarm of the Century", "Sonic Rainboom", "The Cutie Mark Chronicles", "The Return of Harmony", "Luna Eclipsed", "Secret of My Excess", "The Super Speedy Cider Squeezy 6000", "It's About Time", "Ponyville Confidential", and "Magic Duel". Yup, he's the guy who invented parasprites, wrote the "~yay~"/"LOOOUDERRR" scene, introduced us to Discord, based an episode on "The Music Man" and the legend of John Henry, and figured out how to get Twilight to trick Trixie out of the powerful Alicorn Amulet!
But if you think he's going to be satisfied turning in an episode that goes like:
gues wut twilight ur a princes now
omg im a pretty prety princess, i gots wings, omg this is so kewl
BUY OUR NEW TWILIGHT PRINCESS PLAYSET, OOPS WE MEAN PRINCESS TWILIGHT
...that's a failure of imagination on your part, not Larson's.* And that's why there are people all over Twitter with "I BELIEVE IN M.A. LARSON" buttons on their avatars, and why I roll my eyes whenever I hear about alicorn Twilight "ruining" the show or "jumping the shark".
In what context will Twilight's winged-unicorn princesshood take place? Will it be permanent? Temporary? Something Twilight can turn on and off at will? An alternate timeline? A glimpse of the future? I dunno, and although I can make guesses, M.A. Larson's a better writer than I am, and I'd rather just wait till it airs on Feb. 16. And I'm sure it will be awesome!
*(And BTW, it's awfully naive to angrily accuse Hasbro of making Twilight a princess to SELL TOYS. Um, DUH, that's actually been the primary purpose for the existence of "My Little Pony" since the original show premiered way back in 1984.)