Yeah, I'm feeling more and more like trying to make the generic template concept work by adding more features to it (i.e. more complexity) is putting lipstick on a pig. The fundamental premise might just be bad. I am usually a fan of simplicity, but maybe this is a situation where the complexity of being able to assume different animals shapes, with all their strengths and weaknesses, is where the fun is.
Ultimately, I think the current version of druid has one definite problem and one possible problem.
The definite problem is that moon druid is OP at low levels, which is where most games are played. This can make other players resentful ("I thought I was the tank, but apparently this other character, who is also a spell caster, is the tank. As well as the scout."). And it makes most people who play druid want to play moon druid, because why wouldn't you want to be the star almost right out of the gate? And it makes combat hard to balance for DMs, since to make an encounter threatening to the moon druid it becomes lethal to almost everyone else (i.e. the wizard who, at level 2, has 10 HP compared to the moon druids 81 effective HP).
So moon druids are a definite problem and need to be better tuned, especially before level 5.
The possible problem is that maybe the class is too complex and this is making them an unpopular choice. But I'm not so sure that this is actually the case. It might be the case but have we got anything besides speculation to go on? I kind of feel that the game needs complicated classes as well as simple classes. There are some players who really enjoy getting out their monster manual and making lists of all the different animal options that might be useful in different situations. And as a DM, I think it is pretty fun when the druid comes up with an unexpected animal choice.
So, going back to where we started...how much of this could be solved by simply removing this ability from Circle Forms for moon druids: "The rites of your circle grant you the ability to transform into more dangerous animal forms. Starting at 2nd level, you can use your Wild Shape to transform into a beast with a challenge rating as high as 1 (you ignore the Max. CR column of the Beast Shapes table, but must abide by the other limitations there)"? Why not just keep the part that they get at level 6, where they can transform into an animal of up to 1/3 their level?
That would get rid of the problem of moon druids being OP tanks at low levels, and I don't think anyone finds that ability to be unbalanced at level 6, when main tanks already have their extra attacks and a chonky amount of HP themselves.