The problem with MCU villains, when limited to just movies, is that they ultimately don't matter and are just there to be a road block for the hero to punch on.
For example look at Dormammu. The big bad of magic power and the dark dimension yet after being dealt with, in a pretty clever way, there's no news or buzz about the dude since. At the very least an antagonist should leave a lasting impression beyond....checkpoint to the next MCU movie.
Which is why villains like Zemo, Killgrave, Ward, and Killmonger are models for antagonists that the MCU would benefit more from as it would get the audience to invest in their struggle and celebrate when they succeed. A performance or a character trait where the villain has a lasting impact on the audience or the world they interact with.
With that said I still think Malekith is a waste of everyone's time.