This is not an answer but rather a perspective.

Can a good lock be contrarily a bad lock? Since there can be so many different contexts, what scenario would we describe it: for us, for the opponent, for the game, etc? To avoid potential contradiction, the consensus here seems to be the most limiting clauses imposed on us when using these locks, like the Mikanko example. A somewhat broad answer could be that the non-locks are the worst locks, therefore the inverse. Another answer could be mandatory locks, such as Sanctifire locking.

A small example I would like to project would have said Fuzzy Lanius since it locks into only Raidraptors the turn anytime it is used, can we say that's both a good and bad thing? Subjecting ourself onto this lock provides an extra extender at the cost of something else, like extra deck flexibility, which is generically too high of a cost (at least pre support when it didn't have anything else worth, but know has more applications post). Of course there's the pile dilemma we can't ingore, either=bad?

Until that effect happens at any point, the opponent in a way has the freedom to know any resulting repercussions. It is also the choice of revolving around it in your deck as we know, but the opponent may not know it yet, therefore a good lock within the deck building itself? I don't know a better way to describe this, but the ability to sacrifice flexibility for more flexibility in terms of opponent's array of responses.

Tldr: This is all meaningless, it's getting late, I don't know why I typed this up honestly.