Age discrimination is wrong and it is illegal. Your point is well taken. However, Just to add to sailingfun's points about physical capabilities, You can't Be so naïve as to deny that some of the criticism of our more "veteran" flight attendants is justified based on both attitude and appearance. It is not just "juvenile" talk.
Granted, the same could be said of many older pilots. But pilots are not public contact employees to anywhere near the extent that flight attendants are. There is a difference.
It is simply accepting reality to acknowledge that given a choice most passengers would prefer a more "enthusiastic" and yes, more attractive, cabin crew.
Most of our senior flight attendants provide excellent service but please don't insult our intelligence by pretending that the "cat rancher" issue doesn't exist.