I'm sure @Ryan will cover more, but the insanity of Ajax Edit Comments (AEC) shouldn't be a surprise to anyone — simply check the feature list:

- Anonymous comment editing (as if that wasn't hard enough...)
- Spell-checking (WTF?)
- Deleting comments (by both admins as well as original poster)
- Request deletion of a comment (→ queues and operations to manage that)
- Send e-mail to everyone who commented on a post or page
- Move comments between posts
- Remove all links from a comment
- Moderate comments from the frontend
- Custom access permission system
- Undo all operations you do
- 12 different icon sets (certainly contributing to the megabytes)
- 4 different action/icon presets + styling built-in
- Administrative interface for re-arranging elements in the UI
- ...

You wanted anonymous users to be able to edit their comments? That's ~1% of the provided functionality. The other 99% you get for free, whether you like it or not. (Given how many different aspects are touched, you'll dislike it.)

Most likely, it would be most appropriate to start a debate on whether the current WP.org community and infrastructure disallowed this inspired developer to get his hands dirty in WP core, instead of trying to introduce all of this functionality in a single plugin (which is the only choice you see and have when doors are not wide open) — but I'm not in a position to ask such a question. In any case, that is the actual question you need to ask. ;)