@Emile_Parouty hello, welcome and thank you so much for the feedback on your first impressions! I believe it’s very valuable to have such perspective. I’m also sorry, your experience with it wasn’t as pleasant as I believe everyone in Defold would like to, but let me answer you to the points 
This would make a nice “feature request”, but it would be a general case in many more things, generally drag and drop is not widely used in Defold Editor. I found this issue on github:
But perhaps for this specific use case of drag and dropping layers in tilemap there could be another one created. @Agulev is recently doing a ton of additions to Tilemap Editor - what do you think about it? Somehow in GUI the layers can be moved up and down while holding Alt and using arrow keys, but layers in GUI are different.
It reminds me of this 
Actually, you could also change the camera to look at your tilemap from behind!
Not sure, if there is a setting for this that suits everyone - but let me ask this:
Is your expectation based on experience with other game engines or maybe some other tile map editors?
I think this might be addressed in next release actually, but please confirm if such a case is also covered ? @Agulev