I've got middle-aged eyes; the 12 point is just barely big enough to read comfortably with reading glasses. I'd rather have something larger!
I realize I'm in a minority with this - but consider your market. If you're producing a 3.5 product, or an editionless product, you're going for a more mature, stable audience, and may want a larger font to appeal to them. If you're going for cutting edge young players with 4e or a new system all your own, then the 10 or 11 pt will be fine for most of your readers.
12 pt is considered print standard. 16-18 is "large print" size. That's great for us old fogies, but not very practical in a game product. It's why I prefer all my materials in electronic format; I can zoom in...