Its a lot more predictable than "requests", especially if the target population is something like adult citizens and legal permanent residents.
> If the cost remained exactly the same, then either you spread similar benefits across a similar group size, or you spread greatly reduced benefits over a much larger group of people, to the point where it's no longer a living "wage".
Yes, the cost neutral version would be reduced maximum benefit in the short term (though, again, you make the mistake of assuming that the full cost is just benefits, and ignore changes in administrative overhead), while the budget-neutral-by-increased-revenue versions might retain similar maximum benefits.
In that case it would basically just be removing all welfare and giving everyone a tax-cut.
If the cost remained exactly the same, then either you spread similar benefits across a similar group size, or you spread greatly reduced benefits over a much larger group of people, to the point where it's no longer a living "wage".