I have not reached 2000 in reputation yet but I have been told that the retag link is removed for 2k+ users (and reintroduced again at 10k, but in a different shape). It seems to me like it would be a good feature to keep even for 2k+ users as it is a lot smoother than having to see the whole edit page for the post if you just want to retag. As the retag functionality also bypasses the review queue it simply does not make any sense to remove it for 2k+ users.
The retag link is useful for users with at least 500 but less than 2000 reputation because of two reasons:
Clicking retag instead of edit bypasses the peer review.
/edit?tagsonly=truepage has information on how to retag, while the normal
/editpage has information on how to edit, how to format, the peer review process and – of course – the Markdown preview.
Also, a close link gets added at 3000 rep, a delete link at 10k and a protect link at 15k. You could only delay the removal of the retag link, but not avoid it. There's simply not enough space.
Last but not least, having a retag link encourages retagging rather than editing the whole post. More often than not, an improperly tagged question has further problems.1
1 This could explain the edit tags button for 10k users, which should have learned to address all issues of a post at once.