One thing I always wonder with this issue is whether the restrictions on druid armor actually create *fun* at the table.
I see people inventing all sorts of creative ways of getting around the constraints, and that's woderful, but I can't help but feel the vague rules get in the way of enjoying druids.
If the proficiencies simply said they were proficient in Light Armor, Hide, and Shields, I think everyone would be fine. There would be no false expectations. As it is, though, they are teased with half plate (3 AC higher), as long as you can convince your DM to allow pangolin scales and bamboo shields or whatever. Is that constraint fun?
Is the wording that Druids "will not wear" metal armor fun? For me, if a character has a proficiency from somewhere else (being a dwarf, multi-classing, feat) it should be fine, but a straightforward reading means it is not. Is that constraint fun?
For me, it's not. There are ways to get a better AC, but having one class with an arbitrary restriction on proficiencies just seems ungainly.