Well put.
I happen to have discovered that for me, I'm a size queen - but my GF has a friend who is a pro (*******, *******) who won't see bigger endowed clients because she can't take them without getting hurt so bad she gets put out of action (and out of work), and given that she fucks for a living all day you'd think she'd be just the sort of woman who would have worked up to taking anything.....
I find that for me, a thicker cock makes wonderful sensations pressing more against my G-spot, and just giving me a feeling of fullness that is hot. It's also a total turn on to see my cuntlips spread to their max, being pushed in and pulled out by a thick shaft, when I look down or in a mirror (I'm big on fucking in front of mirrors - I'm a particularly visual girl). And I've found recently with BBC toys that at 9" (I haven't had a guy that big - yet ;<') ) the head "bottoms out" and that especially if I'm riding it hard "cowgirl", I sometimes have these crazy orgasms that are unlike anything else..... Also, bigger size creates a lot more sensation and pleasure when doing anal, making it easier for me to actually cum from being assfucked.
That all said, my first black BF (and only, other than a one-timer) was maybe only a bit on the big side of average - but he really knew how to work it. He had a pierced cock, which I definitely thought added some sensation
And he was bi, so maybe he had an edge in teaching me how to relax and enjoy anal, and to cum just from being fucked in my ass.....