c. its an active listening experience as opposed to pushing a button or clicking a mouse
For me this is probably the #1 reason. An album on vinyl forces you to take part in the listening experience, get up at least once to flip the record, take in the artwork and/or liner notes, actually interact with the music. It's the opposite of casual listening, like an aural equivalent of slow food.
As much as I also take advantage of the convenience of CDs, ipod, etc, and like that convenience for what it is, I feel like digital music has had an overall devaluing effect on the music experience for most people. You can get anything you want for free, so why pay for anything? Also, mp3s and burned CDs don't often come with artwork, liner notes, credits, even song titles sometimes. I've heard people say so many times "I don't know the names, but I like number 4 and number 7 best."
Also I like the way they sound and the fun of collecting.