OK, I'll start speculating! You say they're all from hildon teams. In light of that, with Canola seeming to be the most aggressively developed Tablet app, and it being developed under the auspices of the Nokia Institute of Technology, this excerpt from a message Marcelo (the public face of the Canola team) sent me might seem relevant:

"we are not a "integrated" application, in a sense that we don't use hildon, gtk, and we do not agree with the UI guidelines for maemo (they are old, and not good for the device, actually they were even not made for the device, it is based on the nokia 7700 and 7710 touchscreen phones from the past : / )"

(Maybe some old-timers or developers know hildon is on its way out, and this is old news; I don't know; but it seems maybe more than coincidental that Canola is anti-hildon and these hildon programmers are exiting.)