I have no qualms about the term #BostonStrong.
I think its great that a term like this has come out of a tragedy.  To me, it respresents the resilence & determination of the citizens of the Boston area.  It conveys the strength and stubborness of the community.  The idea of "Don't screw with us because we'll get you". It's a label for the people and their actions.  It represents toughness. 
As someone who grew up in the area and set up roots for a number of years, I'm proud of the term.  I've used it as a hashtag in a number of my tweets over the past week.
If this term is spread to the sports teams (as it has), I don't have problems with it.  There's a meaning there and its been a rallying cry.   Sports are so interwined with the community in Boston, it makes perfect sense. 
Obviously there are some people who feel that sports are a little too important.  If they're using something like "Go Celtics, #prayforBoston", I'd roll my eyes a bit but there are people like that. 
#BostonStrong is awesome, IMO.