Still if you look around we are definitely the minority. It seems like some people can't stand the thought of eating alone. Sometimes co-workers will practically beg you to go eat lunch with them if they don't have anyone else to go with. I think people place a stigma on themselves about it even though they won't look twice when they see someone else out eating by themselves.
Wine and some literature or a notepad for creative flourishes are often better company than people... and can help one to take work and life less seriously. This is a situation in which strong service people can really make a restaurant shine. Also, often I find eating alone I am actually able to meet fellow diners, occasionally single and attractive ones, with relative ease!
Similarly, if feedback is requested by staff or I feel compelled to offer it at the end of the meal, I can be honest and open about my impressions and not have to curtail perspective to avoiding looking like a snob to my dining companions. (An aside, is that IMHO one mark of a great restaurant is one that invites and accepts graciously feedback from its patrons.)
France, Romania, and Los Angeles have the most single-dining friendly cultures I've encountered. Holland does have it but it can be a pain in the ass to find quality restaurants, and very hard to find anything done well that deviates from the European cuisine matrix. Much of Asia (Thailand, South India, China, etc.) has a great single dining culture from a more practical perspective: less white tablecloth, multi-course meals and wine lists - more convenient menus and hands down tasty single person optimized relatively-balanced meals, at least for a portion of their cuisine.