Well, yes and no.
DD moved to San Fran in #87 and stayed there for a few years (#109). The comic didn't go bi-monthly until #148, so that's almost 5 years earlier.
Also, while I could agree that DD is best when he's protecting Hell's Kitchen that really kind of limits him as a character to one area of NYC which is pretty small. Not to mention that it's not what it was then. It's not all "grim & gritty" and is actually kinda nice. So it's ok to change it up every now and then.
The only thing constant is change, so we know he'll be back and then we'll have cause to celebrate! Last time he left he had the Black Panther look out for HK. Maybe this time the current Might Avengers can do it. Maybe Elektra will be around, I dunno...