I don't see anything wrong with hostile architecture, per se. What's wrong is hostile architecture in the absence of shelters and housing programs. But the solution isn't giving over playgrounds and store fronts, but to provide housing.
And as someone who has lived in multiple large cities, I've seen firsthand (as an observer, as an acquaintance) a not insubstantial fraction of homeless will simply refuse assistance, whether because of mental problems or drug addiction. So the presence of hostile architecture doesn't necessarily mean shelter doesn't exist, it simply reflects other societal ills.
I don't know how to solve the problem. But railing against the symptoms doesn't help. Filthy public spaces are worse than no public spaces, and no public spaces is precisely what we'll get if we try to address the symptoms without addressing the underlying causes. Parks disappear, buildings are built without public spaces entirely or with "public spaces" inside buildings where security patrol and which become inaccessible after hours, etc.