I'd like to second this. Where I work we get catered lunch, and it's clearly a win-win. Getting food outside the office is at least a 15 minute round-trip and, amazingly, almost always costs more than catering.

We also have a good culture around it - people who don't feel like socializing frequently take food back to their desks instead of eating with everyone else, which I think removes some of the issues people take with the idea.