(I just was typing this for a question which then got closed as a duplicate before I finished. I'll post it here, thus.)
There are several points to think about, here.
The edit bumps questions to front page feature has these goals:
- If a question is edited, maybe it is now easier to answer => People should look at it, and maybe upvote/answer it.
- If an answer is edited, it could now be a good answer => People should look at it to upvote it.
- Maybe an edit made something worse. => People should look at it, and maybe revert the edit, if necessary.
On the other hand, bumping many old questions to the front page has the effect that people don't see the new questions anymore.
For example, in the last some days I edited all questions with "question" in the title on tex.stackexchange.com. After about 6 such edits I got a comment request to slow down ... since my edited questions came faster than new ones. I then changed to a "one per hour" rhythm (on average).
(Some of these questions were further edited then by other users, and I think some even got new answers.)
This is particularly bad for small sites - Stack Overflow has no such problem (for normal editing speeds), though it might affect people who follow the tags which I'm just editing.
So, if you simply don't do this too often, the bumping is not a real problem. (Of course, if multiple people do the same, it again gets a problem ...)
I'm not sure how to solve this - maybe have a kind of "approve" feature so another user will confirm that this edit both
- is not malicious
- does not make the post so much better that it should be bumped
Or, as Michael said, simply put a size limit. But some edits (like adding/removing a "not") can quite change the meaning of a post.