I strongly disagree. While I do not deny the discouragement that putting questions on hold poses, this detriment is clearly outweighed by the advantages.
Closeworthy questions should be put on hold as fast as possible so that they are not answered in this state. Otherwise we run into the problem of answers that get invalidated by an edit, long discussions about opionon-based answers, partial answers and so on. Remember that those questions are problematic because of the answers they receive and putting them on hold has exactly and only this short-term effect: It blocks answers.
If you leave closeworthy questions open for 24 hours, you rely on the community detecting this problem and not answering such questions. I do not think this can work. In particular new users are likely to ignore this, answer the question and thus very likely face discouragement due to a changing question or the inherent problems that made the question closeworthy in the first place. And new answering users are somebody I really would not like to see discouraged.
I would like to mention that the above is backed up with experience from sites which are less active and close much slower than we do.
Another, different problem with your suggestion is that the system is not designed for it. Shifting the culture to your proposal entirely is difficult, so somebody will still flag or vote to close. Then, if I encounter a closeworthy question in the close queue that is younger than 24 hours: What should I do with it? If I close it, we are almost back to the old system. If I leave it open, such questions may never be closed. If I skip it, I leave the decision to those who do not adhere to your proposal and we probably have our close queues crammed like on Stack Overflow.
So, what can and probably should we improve?
When voting to close a question, explain to the asker what is wrong and what they need to do. The close notice does this to some extent, but only to some extent and the asker only sees this after closure (of which they aren’t informed).
When encountering a question in the close queue: Before voting to close, ensure that the problems that put the question there have not yet been resolved.
When you notice that an asker amended a question, retract your close vote.
Reopen questions quickly and whenever you think that a question is now in a state that would not be closed in the first place. Do not vote to leave a question closed just because it is lazy, trivial or has other flaws (that’s what downvotes are for).
If there is a straightforward way to make a question not-closeworthy, do not vote to close, but edit. For example, if a question’s only problem is that it is many questions in one: Do not vote to close but edit it so that only one not-closeworthy question remains (and tell the author what you did and why). Note in particular that one edit from the close queue removes a question from that queue.