Interest in bios depends on how much I like the character, normally I couldn't care less, but if I'm really interested in knowing them I'll take a glance at it. As far as making them, I rather enjoy it. It's a good exercise in fleshing out your characters, and I like to use them to document mental and physical ailments, and noting their physical appearance. (such as things you wouldn't see much during the comic, like scars, birthmarks, etc.) Sometimes adding tidbits of medical info I get from my research, it's kinda fun... even if I may be the only one who'd find learning that kind of stuff interesting. Lmao!
I didn't make one for my comic here, but there is a prototype one I made for a comic posted on another site. Bios aren't very relevant to the story, so if I were to make one for the comic here, I'd probably keep it to my blog and link to it for people who are interested.
I don't normally see a problem if I were to take a look, but sometimes the author doesn't really know what to put, so they have something useless like "she really loves ice cream!". To me, if you were to add an 'interests' section, I'd prefer to see hobbies, or things they do around town, like volunteering at animal shelters. Sorta like looking at a job application, minus the fake crap you put in to get the job.