One of the reasons I got into gaming was minis. I was over at a friend's house when I was 9, and his older brother had some old Grenadier and Ral Partha minis. My dad is a hardcore model railroader, so I always liked minis and building terrain and scenery. I was entranced by the minis, and asked what they were for. When I found out you could use them with gaming, I was hooked.
Over the years, I've accumulated probably 7000 metal minis, about a third of which are painted. I'm a pretty quick painter (1.5-2 hours for a "human sized" mini done carefully), and do a pretty good job at painting them (I've won a couple of painting competitions and do commission work sometimes when time permits.). A lot of my fun of prepping for a game is painting minis, and I find it relaxing- even with my busy schedule now, I try to paint 10-15 minis per month. I've used minis for gaming ever since I started, and while I've played without them, the minis have always been a part of the game for me. Oh, and using unpainted minis drives me NUTS- maybe its the perfectionist in me.
I have picked up a few boxes of the D&D minis, but the random nature kinda bugs me. I have bought probably about 100 of them on Ebay when I wanted a specific monster. I usually repaint and rebase the mini, because let's face it- mass produced and painted plastic minis usually look kinda crappy.