To me it just built up anticipation to see him in the flesh. I also wonder if the juxtaposition of him being cordial in the message and then threatening in person made work for a lot of people regardless of that.
I think you kind of know he is up to something when he offers the droids as a gift. So maybe it is less about what he looks like and more about what he is going to do. Good point though!
Doesn’t work for me unfortunately. Seeing him fully in the hologram (even if it’s a hologram) plus him being talkative in said hologram zaps the mystique for me, even if his plan is admittedly mysterious.