It is a bit like Unix principles (please, don't hit me!) - if program succeeded it should not output anything by default.
$ cp foo bar
$
Problem of course is if something is taking longer time. I prefer microwaves with single ding at the end to one that is beeping every 3 seconds (I have such one at my work). Of course microwaves have also clear progress bar. Android is guilty many times of doing something in background and not showing it at all. I think that abundance of log messages or showing progress is just laziness at users expense.My Roomba talks to me in my language when something is wrong. It is helpful for less common notifications (like clean the brush). But it is annoying for common things - like Roomba notifying that it stuck on the middle of carpet for no apparent reason. In common case I would prefer it to not occur than to have other means of notifying me.
Status lights should be so much dimmer than lights currently most devices have. With all the devices around me it sometimes looks like it's Christmas.
Modal popups are very hard to do right. I think many times it would be better to have simple means of undoing the action with non-modal popup and additional way to undo not that recent actions. I understand that it may be not that easy - i.e. removing something. For example I am baffled that adding a word to dictionary in Google Keyboard needs additional popup (that appears half a second later thanks to useless animation). I would prefer it to just show non obstructing popup with option to undo addition of the word.
I forgot my food in beeping oven constantly, just because I semi-opened it to prevent beeps but did not extract contents because it was too hot. Even when I look at it, the fact that the door is not closed automagically means to my brain that there is nothing inside.
How it should be done: ding once, light inside. Open door -> turn it off.