Why the big gathering?

A lot of the modern church’s efforts center around Sunday big-group gatherings (Sunday services), featuring music, preaching, and programs for the entire family. Others see more intimate gatherings as being more effective. They meet in homes, and still do a lot of the same things (encourage, teach, pray, read the Word, share the sacraments), but in a less institutional way. I’m talking about the whole house church movement. Some try to by a hybrid. They retain the big gatherings, but emphasize what happens in the house churches. I’ve become more convinced that big group gatherings aren’t enough. You need what happens in a more intimate setting. The problem with retaining the big Sunday gathering, though, is that it inevitably overshadows and displaces the more intimate gatherings in almost every example I can think of. I have some honest questions, but not necessarily the answers:

If doing church in a big gathering is less effective than doing church in smaller gatherings, why do we spend so much of our resources on the big gathering? What do the big gatherings do that the small ones can’t? If you believe the small gatherings are more effective than the big ones, why keep having the big ones?

Update: Bill says it well in the comments section:

Here’s what I wanted to know:  Could a small (20) group of people do church? If that size group could do everything a church was supposed to be doing, without programs or buildings or big gatherings then why add those things?

This is the big question for me. Why the million dollar rooms that are used an hour a week? Why the 40% or more of staff time to pull off an event that isn’t as effective as one that takes place in a living room? It doesn’t hurt to ask.