Sizeaddict..I can definately relate. I'm tall and vers,depending on who I'm playing with and so I end up being the dom more often than not.This is probably the most plausible answer...most men are always out searching for something bigger (in a cocksuckers case) or better (in a feeders case). I have one guy that I suck off on a regular basis. He's very tall, his cock is long and very fat, whenever we schedule a session he always shows up, he likes to get rimmed (which is a ++ for me), he could care less about stroking or sucking or even seeing my cock (a true feeder in that respect), and he's not looking for a relationship or any other sort of commitment...sounds like the perfect match. But even so, it's just one hung guy, and like huge cock too much to only taste one. Plus, he doesn't really treat me like the whore I want to be treated like (I won't go into details).
So I find myself searching for others, and I've met plenty, but some of these guys are married or otherwise "straight" have never had another guy suck them...the thrill turns them on, but that doesn't win out over their concern about getting caught or catching a disease, or plain guilt. If the guy is gay, he's not going to limit himself to one cocksucker, and if he's packing a huge tool he doesn't have to, he's got cocksuckers flying at him from all directions, he can afford to have a different cocksucker everyday.
My biggest problem is finding guys that aren't into reciprocation and can truly take control of the session. I'll meet a guy, he'll tell me he's dominant, that he's ok with no recip, and as soon as he walks through the door he's ass naked before the door closes behind him and asking to suck my cock, and I'm standing there having barely gotten my shoes off. I HATE THAT. It screams of desperation, submissiveness, and a general lack of manliness. "I'm" the one that should be stripped naked, exposed, and begging to get my lips and throat used...but i digress...
You also look more like a top than a bottom, at least in my opinion, so I'm sure that contributes to your situation.