IE is usually associated with gaping security holes, which is a little unfair. Adobe is also noted to have awful security. I'm sure if Firefox and Foxit were the leading software used by the majority of people then we'd be hearing similar things said about those softwares re: security.

Having said that, I still think IE and Adobe suck, and try not to use them unless forced, because of the same reason. Popular software is more commonly targeted by criminals. It doesn't help that many (most?) workplaces don't bother to update their software (or wait months to do so), leaving their users and data at risk.