No I think what charm Black Orchid has comes from being brief. I quite like it, but it is quite lightweight fare. I don't know why Who doesn't do more purely historical stories. You can have very interesting villains without there needing to be an alien threat in every. single. episode!
Kinda's great, aside from Nyssa's nap...
Interestingly I just finished watching The Visitation (which sits between Kinda and Black Orchid) which I always enjoy, nice setting, all the regulars get something to do. Even if Nyssa is confined to the Tardis for long periods she is at least doing something not just sleeping (Kinda) or waiting (Earthshock) plus it has Richard Mace, who really must count as one of the best companions we never had
I can see why people like Black Orchid, it's a nice short break between the bigger stories around it, but objectively it fails completely as a piece of drama. It also has the terrible - show the policemen the Tardis so they will let me off a murder charge scene - which is particularly objectionable as it doesn't make any difference anyway and is part of that annoying early 80's trend of anyone being allowed to wander into the Tardis.
I would love to have some pure historicals - they 60's ones are some of the greatest ever Who stories.
I love the Visitation though - looking forward to the special edition - the commentary is one of the best of the range as well