Not only would there be more people on the streets protesting against real or perceived cuts;
there also would be fewer movements based on exclusivist ideologies protesting _in favour of cuts_*
* e.g. racist groups in favour of cutting some kinds of welfare because of racial associations
... also, one pretty practical problem with UBI is that cost of living varies wildly. And if it depends on location then people would register in a high-CoL place and live in a low-CoL place. (Which is what remote work already should be doing, but many companies are resistant to change.)
In theory it makes sense to have easy to administer targeted interventions, because then there's a lot of data (and "touch points" - ie. interaction with the people who actually get some benefit), so it's possible to do proper cost-benefit analyses.
Of course this doesn't work because allocation is over-overpoliticized, people want all kinds of means-testing and other hoops for people to jump through. (Like the classic prove you still have a disability and people with Type I diabetes few years have to get a fucking paper.)
So when it comes to any kind of safety net it should be as automatic as possible, but at least as targeted as negative income tax. UBI might fit depending on one's definition.
I don't exactly know how I feel about those, but I respect those criticisms. I think the grand synthesis is that UBI exists on top of existing safety nets.