Given I love to suck, and occasionally bottom but I'm tight, I prefer guys no bigger than average. I can even be happy with a smaller guy, which makes them so grateful, and easy to get into bed.
They're always getting passed over for the horse cocks, so someone like me who appreciates a "bite size" is very popular with them. And I can do much better oral work on a smaller guy than I can on a jaw breaker, swallow it whole, tongue it all around my mouth... OK, break time.
man...I sure wish more guys thought like you!
Exactly what I mean! Smaller-dicked guys are out there waiting for men to appreciate them, which is just what I honestly do. I tell ya, it's a gold mine. Unfortunately for them (or at least for their dicks) I'm monogamous now.
As for straight guys, which is the OP question, their target audience is women (well, mostly). And I believe most women do think size matters, and so the men want big, too. Plus there may be a dominance display thing going on.
Some physical anthropologists suggest that the disproportionately large human penis is a result of female choice in mating, not the result of wishful thinking on behalf of the males themselves. The theory is that your body is somewhat "designed" by the wishes of the opposite sex, who chooses to mate with individuals displaying certain body characteristics, and to not mate with others, thus preserving those preferred genetic features.