Comic Sans as a font needs no defense. Just like a good band with bad fans, we don't balk at Comic Sans, we balk at the people who use comic sans for inappropriate things. (Or to use a more computery analogy, there's nothing wrong with capital letters or all-caps, but some users use them inappropriately). City memo minutes should not be distributed in Comic Sans. Wedding invitations should probably not be in Comic Sa…
There is definitely an internet lynch mob mentality on this even though the inappropriate use critique is spot on. You'd have to be a brave designer to use it, even in an befitting way. Apps like Balsamiq have dropped it and subbed in look-a-likes just so people have cover to say it isn't Comic Sans. http://www.balsamiq.com/products/mockups/font
However it's bizzarely useful in a way. Say you've got a trail version of an application, you can have a penalty of users who run the app for more than a month without a purchase. Simply flick the font in to Comic Sans. You gain geek credit, even some free blog advertising under the Comic Sans lol bandwagon.
That then creates more posative feedback, people like to read things they are already vaugely familiar with, so you get that natural circle of hate.