As it stands, I have already accidentally clicked "ago" and gone to a comment permalink when I wanted to collapse a thread. Not much better.

Since collapse persists on page loads, hopefully it is better now. Then again, we can un-vote now, so I think we're back to having the behavioral advantages and disadvantages being close enough that it's a toss-up what any particular user thinks is more of a problem.

Why not double-click the comment body to collapse/expand? or maybe some other behavior that isn't creating a click minefield.

But at least now we can undo upvotes/downvotes so it's not as much of an issue as before!

...which is now not a problem.

It's not as much of a problem, but if people are regularly trying and failing to perform the action they want it's a UI wart.

Accidental upvote is a possible wart, collapse on the right is a guaranteed wart.

When in doubt, stick with already established standards.

Reddit does it that way, and I haven't seen any of the developers complain about accidental votes.

Because accidental votes are not a problem when you can undo a vote, which is now possible as well.

I've used HN Enhancement Suite for a while, and that really wasn't a problem.

I feel like it would be worth the trade-off.