At his age and with the package he brings to the game, even if I don't particularly like him, I think he shouldn't be trade.
The problem has more to do with fans' perception of what he is vs what they wish he would be.
The truth is while having all the tools to be one, he's not a power forward. He plays a perimeter game, which is ok for me if the team has other players who are power forwards.
I think Pacioretty will become a very good complementary part in a very good team. Like a very good 20-25 goals second liner. While he doesn't use his size much, it is still an asset as d-men can't knock him off the puck too easily. In fact, he should play WITH a power forward, as his better season with Cole showed.
And don't forget he's developping a good game on the PK. It's rare to have a young player who's big and fast, quite good on the PK, and able to score 20 goals. But like I said, the team does need a player who would play like we wish he could play.
So I say keep him. But of course, if a nice offer is made, he's definitively not untouchable.