There isn't any negative emotion associated with free stuff. Free stuff is great.
The issue is that there is pretty solid social ... I don't want to say understanding, perhaps suspicion is the right word ... that giving out free stuff hasn't ever worked well.
So the political faction that likes the idea of free stuff comes up with a reason that this scheme will work - trying very hard to come up with a framework where people get to consume stuff without necessarily having to do the work to produce an equivalent amount of stuff.
Much like a perpetual motion scheme, the system gets more complicated to the point where eventually nobody can explain why this specific system can't work ... but there is a core relationship here that needs to be broken, and the debate needs to centre around whether it has been broken this time. It cannot be hand-waved away. The enormous costs associated with a UBI are an important factor and there are questions about whether it can be sustained long term.