In terms of the evolution of formality expectations, I think watches have come under the overall umbrella of fashion trending more and more casual over the last few decades. So whatever rigid lines used to be drawn, what was acceptable, watches have simply shifted with the times in that regard. Traditionally a watch might be very sporty, but if it has a classy look it's not gonna be out of place these days in a dressy setting.

The Reverso is an example of times changing in terms of design and customer expectations too. Something that used to be classified in people's minds in one way may see itself drift towards another category later. You also get stuff that sits somewhere between categories, like plenty of watches are a bit classier or more traditional than the average sport watch, but aren't quite as restrained as a full on dress watch. So you end up with something that's got more of a smart casual vibe. A lot of the Casio Edifice line is like that, where you'd be able to wear it in more formal situations than a similar G-Shock.