In both my own puzzles, and in other people's puzzles, I have noticed a lot of Morse code. Obviously, going overboard with this or other common puzzle-making devices can detract from how fun the puzzle is. But there are some pretty fun ways to use Morse code that can make it less obvious that Morse code is being used.
For example, in one of my puzzles, I made use of the official lengths of dots and dashes, as well as the lengths of pauses between them and between letters to make a Morse code part that consists only of dots, and you have to use the amount of black and white dots to find the answer. I have seen other puzzles in which Morse code is used, either in a creative way, or simply in a fun puzzle, and I see it used enough, and use it often myself, that I feel it merits its own tag.
Puzzle creators extremely often use tags to hint at the kind of puzzle, as well as the methodology used to make and/or solve it. Having a Morse code tag would allow them to convey that fact as well. I feel this way, and I would like to know how others feel about this as well.
Edit: As I was making this question, I checked to see if a Morse code tag had been added, and I accidentally added one. I mention this because I know that moderators will be able to see that I made a tag, and I wanted to start a discussion on it and basically get the moderators' permission before I went ahead and made the tag so that I wouldn't overstep my authority (or lack of it), seeing as the moderators are the ones who are supposed to keep order and oversee things around here.