It makes everyone feel they're a hip startup. I mean, my IRC client has been doing drag and drop file sharing and image URL inline thumbnailing for... 10 years. The HipChat client is nice, but let's be real, it's just a nice client for a handicapped implementation of XMPP. I'm forced to use HipChat at work and use Adium to connect. I've even got the emoticon set, and message styles to match.

They can't even program a mobile app that reconnects me automatically (unless that's changed recently).