Anyhow, the first step to a solving a problem is identifying it; they need not be atomic operations.
"...and their improvement is made to depend on allocating more resources to the management of hospitals, schools, and other agencies in question."
That's where he veers into making a policy recommendation (defunding social institutions), and where he is no longer engaging in critical theory but in pushing a particular policy agenda, therefore opening his critique (some of which I'd even agree with) to practical criticism from people with more skin in the game.
I agree if his long-form critique takes the structure you claim, it is of poor quality because claiming desires in not critical of anything.
However, I do disagree with your claim the critique alone is not helpful. A harsh, well formed critique is typically the very first pillar in driving change. Expecting identification and resolution in the same piece is asking too much.
I would argue to say that a critique being invalidated because it somehow must include both framing and describing a phenomenon as well as suggesting changes, each weighted by their feasibility in remedying the systemic woes, is much more fallacious.
There's a recording of a teacher asking how to infuse lessons from deschooling into her classroom and his response is basically "you can't". He's actually a bit rude about it tbh.
Illich was opposed to schooling. He would have said he was in favor of "education". Nailing down what that would mean on the scale of a society, aside from learning webs, is a bit elusive.
I think Illich provided a fantastic prognosis of certain problems but didn't develop workable solutions.