I don't like Undo option very much. When playing Dominion in real life with cards it never happened someone asked to go back some step. Everybody are just aware that they should play carefully and not make hasty moves. I understand that sometimes misclick happens because it happens to me as well, but in general people just don't pay attention. Anyway, that is my opinion and I don't ask for Undo nor I ever did, but also don't want to grant it and when I don't people get mad and become rude. I don't want to explain to everybody at the beginning of the game that I'm not going to grant them Undo, so it would be nice to have an option for every player to click on a button that would disable Undo request for the game. In one of the announcements even not granting Undos was characterized as "unfriendly". I don't think it was necessary to label somebody's opinion like this.
I'm sorry, but I disagree with you in a couple of instances, and I will tell you what they are. 1st, if I play Crown, I sometimes do so forgetting to end my action phase. I feel this is a very easy mistake, and I assure you the mistake is not made because I am playing too fast. The 2nd reason is Enchantress. I actually had this come up. I read the log, saw my opponent played Enchantress and went ahead and played a terminal card. It ends up that the Enchantress they played was in response to my Enchantress. I misread the log. I did not play fast. In that instance, my opponent refused me the undo. I personally felt that was very, very, very unsportsmanshiplike because it was obvious what happened.
Yes, mistakes happen because people play too fast, but there are legit mistakes as well, and I think outright refusing undos in the two circumstances I mentioned above are rude. But, that's how I feel.
Also, for the record, irl, you would never tell someone they couldn't play Crown because they failed to announce the end of their action phase, and irl you can see if Enchantress is in play.