This is a problem for me and will probably eventually be a problem for others.
What would happen without this feature:
1st Time: Flag your post with a custom moderation message to have a mod edit your post for you.
All continuing Times: PM a mod asking to edit the message for you.
With this feature:
Every Time: Edit the post yourself, without the need of a moderator-in-the-middle.
Personally, I prefer not being able to edit posts after a certain period of time. Discourse, while not like most other discussion software, is intelligently thought out, and this is the product of such thought.
Gotta agree with @FerusGrim, for the most part it is only sensible to stop editing after a certain time. There may be exceptions for certain posts, but it shouldn’t be disabled completely.
Then what about enabling it for specific posts (or even categories)? Like, you ask a moderator to be able to edit it for an unlimited time, and he adds your post to a list of exceptions…!?
Why would you not want someone to edit his posts later, especially in categories like WIP Plugins?