Y'know, stuff like this bugs me, for many reasons.
Now, granted, this is a relatively harmless little bit of, well, fan-fiction poetry. It hurts no one, and it's all good. That said, the underlying entitlement is fairly oppressive, honestly. The inference of a continuing relationship that, simply...Does. Not. Exist.
"Don't be sad, Matthew?" He decided to leave the show, for his own reasons, and he's off to make a movie with Ryan Gosling. Why in the hell would he be sad? I'm sure he's well aware that where he is now is almost entirely because he said "yes" to Doctor Who. If he doesn't, he's a fool. He has to know that maintaining a relationship with the fans will be useful for his future career.
And, make no mistake, that is what Matt Smith is thinking about right now. What comes next, and how to make his time in the spotlight not about the show, but about him. The way the show, itself, has changed will help him with that, but...if you think he's laying awake nights worried about how long Whovians have to wait for the next series to begin, I think you need a reality check.
"Go to them?" Really? Like he's some sort of holy man?
The 11th (12th if the John Hurt rumors are clear) Doctor is gone, or will be soon. Just like the ten actors before him. They'll move on, to whatever level of success they may be destined for, and do some interviews from time to time.
I'll tell you this, I don't get the impression that ANY of the Doctors from the newer incarnation of the show are interested in carrying on the fan service that people like Peter Davison and Colin Baker have done. You're not going to see Tennant, Smith or Eccelston as fixtures on the convention circuit (MAYBE Capaldi, but only because of his deep ties to Who fandom...he might enjoy it), because, in the way that the show has become personality-driven, these guys are now on the radar of Hollywood.
I think that every fanbase has to go though a point of realization. Where you see that while I'm sure Matt Smith does love the fans, the power, adulation, and attention they brought, he doesn't LOVE you. He's not going to jump in front of a bus for a fan, he's not going to place fans over personal relationships, and he doesn't owe you any of that.
He owes you the performances he's already given that you enjoyed. So, his part of the deal is done, baby.
He doesn't have to hold your hand through the change to a new Doctor, or assure you that it's all OK. Of course it's OK, it's Doctor Who! Regeneration is the name of the game.