I see 2 schools on this
1: Younger cats who still havn't had the demands of rent, mortgages, or kids being altruistic to music
2: Older cats who have scraped and struggled ( and sometimes succeeded) to stay working in the music business.
The problem is.... Music is the only business that people would do for free. How many people wan't to sit in with the band. Anyone posting here ask yourself when is the last time you asked to sit in with your garbage man as he collects, or your dentist when he drills? Now the drilling part sounds like fun but it takes skill and practice to do it right or its painful. The more educated and experienced in music you become, the more you can deliver a professional product to a public. If you want to give it away, I can't stop you just as I wouldn't stop you from handing me over half of the bar receipts from a club.
I am the same age as the OP and have had enough resume filling stuff to espouse this. I currently do clubdates and even though I love most of my bands and would play for free with them ( ah, but where?) I'm in reality just an expensive taxi. My meter starts running at the start time and I'm done 4 hours later or there's more money due me. I also know that the people who book these jobs make a big chunk of change on the gig so I don't give my services away . I'm also responsible for an enormous repetoire, and have to deal with the stuffiest clients and the rudest Maitr` D's( This week I have an email with a list of 15 things I can and can't do at this club) maintain a clean tux and show up on time. It costs money to make money.
Sorry for all the wind but to sum it up:
If your playing someone elses material, you better be gettin' paid