Allowing to undo is a vast subject, and it all depends on the kind of undoing you want. I'll try to express the opinion of BGA admins since we talked about it a few times already, but they will correct me if I'm wrong ^^
They don't pay as much attention as you'd want on making sure you can't
misclick. They develop and play games using laptops so they often don't think about tablets. In my first game here, Quoridor, you can very easily misclick. But in the last game I did, Sobek, there is a required confirmation each time you could misclick. Mostly because 2 years ago tablets weren't as popular as they are now.
So yes older games could be improved to prevent misclicks, but improving years old games could lead to lots of new bugs. Please realize a dev wastes between a tenth and a quarter of his/her time fixing bugs; since improving an old game is prone to raise even more bugs, there is little chance he/she'll take the risk. Harsh truth, I know. If you want to fix games I worked on (and all the new inevitable bugs ^^) please contact me!
BGA admins are against undoing
multiple actions because it makes opponent actions unreadable.
They allowed me to do so for Time Masters but in this game you're supposed to control time so it's the only exception. I wish there were an option to allow it for beginners / low ELO players only. Just in case it were to become available, I'll program and disable the possibility to undo multiple actions in all my next games.
This feature is way too complex to add to an existing game, so existing games without it will never allow it.
They want
multistep actions to be cancellable before they are completed, but even Sobek which I worked really hard on doesn't allow it: when you play a character card, you have to apply its effect, you can't retract. It would have required way more work I preferred to put in other things. This won't happen in my next games, but most of my first 6 still have this flaw.
Here as well, improving a game could lead to more bugs and less fun adapting new games.
When your action could be a
mistake, admins make sure that the game pops up a confirmation dialog. This requires some work experienced players won't even notice, but the impact of preventing a disaster when your playing your very first games is so important it's worth the effort.
Thank you for this discussion, seeing that you care about as small a feature as an undo button motivates me into going the extra mile.