Yes, yes, they give glory to God and all that. But there's something really economically appalling about an ornate and architecturally expensive building that is used only two hours a week. Better to put up a simpler structure and spend the rest of the money on a homeless shelter. I don't think that God is glorified by waste, but he is glorified by love for the poor and downtrodden.
On this subject, Henry Neufield writes:
But picture the standard church sanctuary, steeple, pews, pulpit, altar area, and so forth. The building, the room, and the furniture all serve for a couple of hours per week. Many of you will point out that you have other meetings in that sanctuary–committee meetings, youth meetings, classes, and so forth. But notice that the room isn’t really designed for those things, and you’re actually working around the architecture and interior design in order to use that space for that purpose. It’s true that there are many newer buildings, especially amongst small, non-denominational churches that are much more flexible, and much better designed for multiple uses. Even so, I would ask you to look at the schedule of use for your office building, the conference room at your place of work, and similar structures, and consider the cost involved and the amount of use.
I don’t have statistics in hand, but in my experience, churches spending as little as 5% of their money on outreach regard themselves as “mission oriented.” Add to that evangelism and budgeting for charitable projects, and you’ll get the total spending for outreach. (Don’t forget the salaries of staff members who are assigned to such tasks.) Look at your own church budget. How much of your money goes to maintaining facilities and paying people to maintain the membership. How much of the spending goes to people in the club?
UPDATE: Henry Neufield adds further thoughts on this topic.