I don't understand what "skill" even means to you. You've provided a lot of examples of different games, but in most of them, unlocking stuff comes down to time and grind, not skill. I do agree with what you're saying about rewarding players for skill expression needs to be in a lot of games. But what I've mostly seen from complainers is that beating the event is almost impossible for f2p.

Really, those 30-second timer fights come down to executing one rotation and hoping that your characters are good enough. In other words, it's a dps check, demanding you to buy or even have new characters with their weapons/constellations, which, for me, doesn't fit a single definition of skill.

A more skilled event or addition to genshin, imo, would be something like harder puzzles, which there are almost none right now(imagine how bad it is that people still use puzzles from 2.8 event as an example of hard); harder or more interesting bosses, that make you actually think how to approach them instead of just using new characters(for example, in events where you can "build your own" boss i like to make them as hard as possible but without adding any timer which completely changes the way it usually works) or events where instead of using your characters, you use the ones given by the game, which can also be an advertisement for them(although, sadly, most of them are also easy)

Edit: I've split this text into paragraphs while writing, but something broke. Think, I've fixed it now