Short, sweet, to the point, if a publisher cancels your favorite MMO, I say you have the right to be mad. Forever.
This isn't because I think all of the companies should be forced to support their old products indefinitely, or because I think they should keep running unprofitable games. It's because if you aren't going to get worked up about whether the entertainment you love is available to you, who is? Unfortunately, or fortunately, you are your own consumer advocate, and if you stop advocating, why should they give a shit?
Not that your voice, pissing in the wind, is going to make tons of difference. Still, it's your voice, and if it ain't speaking for you, who is it speaking for?