Ouch. I hear you.
My first novel was sent to Del Rey 18 years ago by my first agent. Needless to say, nothing happened, and I concentrated on a 'real job' until the writing bug bit me again a couple of years ago. Interns are famous agents now. My first agent no longer reps my genre. Cover art styles have changed. Writing styles have changed -- thank god, mine certainly has!
I look at the fresh-faced twenty-something ingenue agents (who all seem to be repping the same urban fantasy novel with minor plot changes) and wonder 'Can this person actually sell a book set in a secondary world older than she is? And has she read anything published before 1998?'
On the other hand, I'm hesitant to query any agents near retirement. They may be stars in the business, but many of them aren't taking new clients. And of those that are, how soon will their clients have to find a new agent all over again?
We've been at this way too long, certainly.