Why would you want ligatures? I would prefer to see text as it actually is, not combining multiple characters into one. I can't trust what I am seeing if I know the text might be something it is not.
Also ligatures are optional, you aren't affected if you don't like the feature.
I guess I'm surprised that such a crucial feature isn't standard in everything if you can't even properly display a common language like Arabic without it.
Some prefer text to be seen as it was meant to be, so that === ugliness that can't be fixed at the source due to bad unicode support can at least be fixed at the output