It's my perception that not only has the quantity of forum users declined, but so has the quality. Years ago, users took it in stride when they had to investigate the forum software to discover how to make things happen. Now, users have trouble figuring out how to post and blame the site for being "unfriendly."
Back then, a user might ask what they needed to do on their end if the forum didn't display correctly in their browser. Now, users demand that the site be rewritten to accommodate their gadget of the day and their lackluster browsers.
Maybe I'm just an old fogie shaking my fist at the kids, telling them to get off my lawn, but that's the way I see how things have changed in the last 10 years.