I was recently involved with this type of discussion with a friend who owns a very large Black Lab and a very large Border Collie. He has a Dirt Devil bagless featherlite (with that horrible pleated filter in the middle). I gave him a Simplicity Symmetry to try out. He's a fireman, so only vacuums once a week. The bin in the bagless would fill two or three times in one trip around the house, he banged out the filter at the end during the final emptying.
The Simplicity cleaned fine. Since Kevin couldn't see the dirt, he kept on vacuuming until the dirt backed up in the hose. There's so much dog hair, dog food, mud from their paws, etc. Two big dogs make one large mess of a house. The problem with the bags is the Kevin would never buy them. Not because he was opposed to spending the money, but because they didn't carry them at wal-mart. He hated the Simplicity because it USED bags.
While most vacuum collectors go on and on about how much they hate bagless - bagless wasn't designed for us. It was designed for someone like my friend Kevin. I realized that for him, bagless was a godsend, even the dreaded pleated filter was better than a bag - because he didn't have to buy them. Wound up giving him a simple Hoover WindtunnelMAX Multi-Cyclonic and he couldn't he happier with it. After two months, and about 20 full bins of dirt, the pre-motor filter still passed just as much air as when the machine was new. Just a slight coating of fine dust.
There are so many people for whom bags are NOT the answer. We must realize that most vacuum consumers are not like us - the 'sanitary' aspect of the disposable bag (invented by Air-Way in 1920) is no longer a viable option for many folks - people with large families or pets. We have to understand that to MOST people, disposable bags are a total waste of money - you're throwing the cost of the bag into the trash can. No matter how WE feel about bags/bagless - it's the ultimate consumer who drives vacuum manufacturers to make the types of cleaners they do. Most people consider bagless to be a step ABOVE bags - by eliminating the need to remember to purchase something AND by being able to see how much dirt is collected and when it's time to empty.