Older men don't need hotter looking girls or viagra. They need women with some interest and enthusiasm. A lot of young good looking women think their share of the sex act is being available. "Hey I'm here, do your stuff". Not much of a turn on to a man out of adolescence.
Only boys under 18 think there is some sort of positive correlation between a woman's looks and her interest (or capabilities) in sex. Plenty of hotties aren't worth diddly in the sack, which makes them pretty undesirable after the first time, unless you're 18.
BTW, skinny chicks with big fake boobs are not hot.