One big problem is that getting stuck might mean spilling a great deal of potentially staining cleaning fluid in one spot.
Also, one task like vacuuming can be done at random because there is no series of events. Just vacuum. This guy vacuums then wet-cleans then mops up. What happens to the dirty water receptacle when a missed wet-hair-ball gets trapped in there?
I personally don't mind mopping. It's fast. Scrubbing bathroom tiles and bathtubs are what I really hate doing.
I do plan on getting a regular Roomba sometime soon.