I often see revision histories of pages like this https://de.wikipedia.org/w/index.php?title=Liste_der_Stolpersteine_im_Landkreis_und_in_der_Stadt_Gotha&action=history. This happens quite often when a user is preparing the page in his/her namespace and then move it to the to article namespace. Also later user prefer to make several commits for safety reasons. For me such many revisions mostly do not create any benefit for later. Why not allowing the user to amend/merge a current commit with the previous one? This would create a more clean history and would save some space on the harddisks of the server. Due to my wording you maybe saw that i am coming from version control software like git where this is naturally supported and widely used to have clean revision trees.
Topic on Project:Support desk
Well, there's a "preview changes" button to avoid saving the edit, maybe some users should be taught to use it more often :)
Your proposal is a sensible one. But that change isn't straightforward, because it could create problems with edit conflict detection. Also, assume you save the current permalink to share that version of the page, and then the last editor changes the page again, the permalink will not reflect the text of the page at that revision (of course it isn't consistent currently because templates can also change). It would be also inconsistent in Special:RecentChanges to whoever reviewed an edit and then the edit is changed.
I'd also say that disk space is very cheap, specially for wikitext.
You may want to open a BUGREPORT for this (if none exists already).