Of course it's not. Why would it be?
Perfect pitch is a good trick, but all it's really useful for is getting good marks in your aural skills classes.
I have perfect pitch, and, according to my uni results, I'm a damn good composer. However, the two things aren't related.
The only thing that my sense of pitch is useful for is that I know exactly what note/s I want, which means that I can compose without needing an instrument nearby to test things out on. People without perfect pitch but with a good sense of relative pitch (which is far, far more valuable than perfect pitch (and I'm pretty sure that mine would have developed faster without my perfect pitch, as my tendency is to focus on individual notes rather than the difference between them, and because transposed intervals sound different: to me, there are 84 possible major 3rd sounds on my piano, each noticeably different) can just work out by interval what they're doing, starting on any note and transposing to the right pitch as soon as they get near an instrument. Which, admittedly, is slower, and I'd find it quite painful, but it's not a huge hindrance.
Now for the problems related to it.
Firstly, because of my sensitivity to differences in pitch, each note sounds qualitatively different. I often forget that not everyone experiences sound in this way, and because of this, in the past I've tended to focus too much on pitch structures in my music, to the detriment of the other elements of music.
The second big problem I have is in writing vocal music: my teacher always complained that my parts were very difficult for anyone without perfect pitch to sing (which I disagreed with; all the singers needed is good relative pitch).
Far more valuable than perfect pitch to the composer are:
A knowledge of all instruments; their ranges, how they sound in their different registers, how they sound in combination, what things are not possible on certain instruments (for example, certain trills are not possible on some instruments).
A decent sense of relative pitch.
The ability to step outside of one's work and assess it critically, and to work and work on it until it becomes something worth hearing.