Lots of people have rollerbags with just 2-3 days worth of clothes in them, and they fit just fine in the overhead bins. My bag is designed to go up there and it fits longwise very well, particularly in the new aircraft. Carrying it on saves me lots of time, as I don't have to stand in line at the ticket counter before the flight, nor hang around the baggage carousel afterward.

I first saw the "pillow trick" applied by a flight attendant, and he got the bin door to close nicely. Most roller bags will fit long-wise in the new -700 aircraft, allowing more room for coats and jackets now that winter is upon us.

I use overhead bin space about 50% of the time I fly. Sometimes it's a 22-inch rollerbag, and sometimes it's my smaller computer rollerbag. Either way, it 50% of passengers use overhead space (and use it wisely), there shouldn't be a problem accommodating everyone.