I assume that you have already got a grasp of what the new MLP show is about and etc. As for why people like it, I can see some reasons. The jokes are better than most of the ones in other kids shows and the writing isn't too bad. However, that doesn't mean the writing is good or that the jokes are as funny as everyone makes them out to be. So basically, people started liking the show is because it isn't as bad as other kids shows.
TL,DR Version: You know what the new MLP is by now, people like the show because it's not as bad as other kids shows, let me get back to watching Digimon Tamers.
TL,DR Version: You know what the new MLP is by now, people like the show because it's not as bad as other kids shows, let me get back to watching Digimon Tamers.