As Markus wrote elsewhere, the requirement to confirm "End Actions" in all the cases where you have Villagers but no use case as with Diadem was a much bigger nuisance. Due to cards like Venuture, the Diadem might not even be in your hand for it to be relevant.
People have different ideas what to do about this, we'll see what will be implemented until the full release.
When I have Diadem in hand, the game still goes straight from my actions phase to my buy phase when I have no more actions, so it doesn't give me a chance to spend Villagers.
- If you're in your action phase and nothing else is currently happening (= you're not in the middle of playing some card) you can click the villager icon in the status bar to use a villager.
Thanks for this tip. However, if I hadn't come to this thread, I wouldn't have had any idea that I could do this, because it's not documented anywhere (or an option that I can envision using in any other situations).