Yeah, still a connection to the ground: just happens to be through a half-dozen uke vs. a through a tatami mat, 6-inch-high geta / heels or a soapbox. Maybe those uke knows what it's like to become one of the bows supporting nage's center when IP/IS is in play, and they're just not up to the demands such a role requires.
Audiences are impressed by multiple ukes, of course. If one's good, abunch is better, right? It's always a crowd-pleaser.
A couple of years ago, a local museum staged an Asian arts extravaganza that included a kungfu troupe whose piece de resistance
was having 20 audience members line up to push on one of the troupe performers.You know... each guy pushes against the shoulders of the guy in front of him, and the one in the front of the line actually has his hands on the kungfu guy. They couldn't budge him. The crowd loved it! Would they have been as impressed to see one guy pushing?