Hello,
Indeed, tiling being equal for X and Y is hard-coded in the shaders used in the 3D View. You would currently need to edit your own shaders for the 3D View in order to split those controls. I have raised your suggestion to the rest of the team for internal discussion.
Regarding the default value of the materials' Height Scale property, I suggest setting up the value you need to be the new default, then using the 'Save Current State as Default' option in the 3D View's 'Scene' menu. Setting
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