Size, like most things, matters to some people, one way or another. I have seen more than one advertisement in search of men with small penises.

ObSongs (TTTO "Pop Goes the Weasel"):

Long and thin goes too far in
And doesn't please the ladies.
Short and thick will do the trick
And bring out proper babies.
Our Mary did it once --
Once was once too many.
Wasn't she a silly dunce?
Did it for a penny.