Reasons...
*Dwight respects Doc and our whole team- he's only been to the finals once and he's sick of playing for a half contender whilst his legs get older.
*The C's have beaten up on him for much of his career- except when KG was out, and they still had a hard time then.
* Howard has stated he wants to go to a championship organisation.
*In my opinion, Doc putting Howard out there on All Star Weekend with the big four was a statement- a planting of a seed, maybe even a nurturing of a seed.
*reading an interview a few months back on some French site where Howard stated he would work with Doc and Rondo in the summer to improve his passing skills.(something which went by unnoticed as the lockout began and hasn't caught much attention).This can only be a GOOD THING!
*The Lakers have been touted as his number one choice, but with Jimmy Buss running things (the younger son of Jerry, who hired Mike Brown and dogged Brian Shaw for the job), they are much more likely to build around Bynum. I don't know why but Jimmy LOVES Bynum and him doing a straight trade for Howard is highly unlikely- the Lakers won't take on the terrible contracts of the fillers that will get thrown in ie: Gilbert, Hedo, Vince (FA now anyway).
Anyway, this is all just my opinion, but I think a lot of C's fans aren't giving our organisation enough credit.
New Jersey has a shot, but Howard seems more likely to put his faith in an organisation that has proven itself and has the superstar point guard + coach combo that we have.
You can argue that he wants the spotlight in the big city, but Boston is a big city when it comes to the NBA. Sure the weather sucks at times, but the Celtics have a winning culture, and that's what Howard, as a basketball player, wants.