Some users may vote to close a question and then perform other tasks, ignoring that question.
Other people might indeed give a few suggestions, but may find the question is getting multiple edits or updated frequently, so they might decide to, say, perform other tasks again and then perhaps return to the question to check on its status, assuming they do remember to return to it.
There might be more possible cases, but my point is, in either of the two above cases, one cannot assume said users will go and check the re-open queue. They might think the question's core idea doesn't fit on that particular SE and perhaps no amount of edits can save the question, they might think OP keeps editing the question to attempt to improve it and they're still not satisfied with the question for some reason, so they may keep their vote to close and ignore the question, etc. What I'm trying to say is that users who vote to close should not be automatically expected to remember to retract their vote once the question has improved to a satisfactory enough level.
The re-open queue has its advantages: It's already an established feature, and works in conjunction in a good way with the other queues as well. Possible disadvantages may include: Users not being aware of the existence of said re-open queue (I was not really aware it existed, as an example, and if I was, I may have probably forgot about it back then), and it requires the users to remember to go to the queue, which I think not all users might remember, perhaps especially users who visit it only once in a while.
Therefore, I propose that, when an on-hold question is edited by the OP, all the close voters are notified of this through the usual notification system, since I think it is a more visible place than the re-open queue.
Maybe there should be a sort of reasonable (i.e not too short, not too long) "cooldown" between notifications, for on-hold questions that are edited on a more frequent basis, and maybe a similar system could be used for closed questions rather than just on-hold ones, but that I think is best discussed in other meta questions once consensus is first gathered on this kind of "main" meta question about it.