I'm sure that sometimes unexpected collaboration may happen that might have a small tangible benefit to a company but I can guarantee you that most companies do not need this and the benefits of a work from home culture on the whole city and America's general mental health will be better than whatever new feature you cooked up over your company provided lunch.
imagine the problems working from home would solve: housing costs, high density living, pollution, no commute time, improved communities, improved family life.
The odd piece of collaboration that may come out of lunch chat is really not worth the pain that our cities and resident workers are going through. Can't afford a decent sized house? Probably because everyone wants to be close to work so you're priced out. You'll feel the pain when you get married and want kids; very long commute or sub-standard living conditions, great choice...
Like you said, I'm sure small things will be missed but employees having a great standard of living is likely going to do the company more good than not. I do admit that we would need a cultural shift for this to really work though.