@starbreaker Mostly, yes--a UBI would definitely be a change for the positive for workers. However, assuming that "working" pays more on top of UBI, or exceeds it enough to make it worthwhile, there is nothing to prevent companies from discriminatory hiring. The labor pool doesn't change much from their perspective.
Despite that, UBI has so many other benefits (including insurance against a downturn in labor needs) that it's a must have.