I think alot of it depends on your style. I've heard that rule also, and personally think it's silly. Most large rooms need more than 1 light fixture anyway. For a great room, 2 or 3 smaller fixtures lined up with the furniture placement (sofa, dining table, etc.) works much better. But I'm not sure that is a cost saving measure. For bedrooms and family rooms, I still like a smaller fixture and sconces. It's just cozy. Some people like to use alot of recessed lighting instead of large expensive chandeliers. Kitchens are a whole different category and I'm still struggling with that one. I love the look of some large fixtures as focal points (large lanterns in an entry for example), but often I find them to be ostentatious if they are too large.

Although, take my thoughts with a grain of salt... I'll walk into a decorated Restoration Hardware with their ginormous lights and come home ready to fit them in our build! They do look awfully cool. But I've seen lovely homes do a more understated approach to good lighting with great results, and that is what I'm hoping to mimic.