Like I posted on Yahtzee's article, I wrote a long drawn out response on my personal blog, but Ill summarize it here. I think that the implied argument Yahtzee was making is 2 fold - first that gamer has a negative stereotype that we don't necessarily want to be associated with, and second that the term gamer is superfluous because gaming is pervasive in society.
The stereotype - easiest way to change that is to apply the term to yourself and break the stereotype. There's really not other way to change it other than by doing. A stereotype was created by doing, it can only be changed by doing.
Now, as for requiring a term to describe those, I termed us as those who have an exceptional interest in gaming, or an above average interest in gaming. Right now, in addition to the mouth-breathers and neck-beards, gamer typically refers to someone who has more interest in gaming than the average person. Yahtzee's argument was that you don't call someone who likes movies a moviegoer, and its true we don't. Going to movies is implied in social participation. But we do have a term for those who are exceptionally interested in movies - movie-buffs.
The primary difference here is that the 'naked' term gamer still describes those of us who are more interested in gaming than the average person, whereas for movies (and other activities) we typically append a modifier to describe those who are really interested in games. I think that although the term gamer is probably overly generic at this point and when loosely applied applies describes the vast majority of the population, we still need a distinction to describe those who have a strong, above average interest in gaming.
To read my full response -
http://www.rogue-gamer.com/2010/08/gamer-is-bad-word-i-mean-what.html