I assume that because you didn't write about each of the other items on the list, you agree that those are actually downsides. However, most of the other arguments you provide rest on the premise that "the demand for low skill human labor will drop very close to zero as most menial jobs and quite many more complex jobs can be automated." This assertion is not supported by historical precedent: every time something has been created to reduce labor, we just find other ways to keep people busy, increasing the standard of living. Yes, the labor market isn't quite as fluid as we would like. Yes, it might take a generation or two for things to settle down (as it did during the industrial and green revolutions). But no, we won't run out of jobs.
many people will probably be working part time still, and contribute to a number of things via which they can get their sense of achievement.
That's kind of a vague statement and even if I assume that you're right and that "many people" will continue working part time you have left out a large segment of the population. Where will they get their sense of achievement (assuming they're not very religious)?
because even though the difference between a low wage job and being on the benefits might not be more than a few hundred euros that few hundred euros more in disposable income is a significant improvement in one's standard of living.
Right, and we want to keep it that way, instead of making that difference smaller. When it comes to money, we get diminishing marginal returns for every extra dollar. When living on UBI is comfortable, we've lost the "significant improvement" incentive
Throwing money at the poor doesn't make them less poor?
This is the point when I wonder if you actually read what I wrote. I guess you did to be able to pick that one out, but I did say "The essential issue is that it is not just a lack of money that makes the poor "poor," but an entire environment." Being poor is not a purely economic problem. It's chiefly a social problem and yes, throwing money at the poor won't fix the social problem.
the history will likely look back at the guys who thought UBI was the end of the world as akin to those who said the ending of slavery would cause major economic meltdowns
I would love it if we could avoid this sort of thing. Comparing me to an anti-abolitionist is not only insulting but completely unrelated to the issue. Not only did I never say that "UBI [is] the end of the world" but it's completely different from slavery. Slavery is morally wrong... and so is freeloading. Just claiming "people will say I'm right in the future" doesn't make your idea any more correct in the present.
Even if you were right, these things aren't in the present. You're arguing that we will need UBI at some point, but use that as justification for it's creation now. How can you justify fixing a problem that doesn't even yet exist?