Scale Shape Layer From Corner Without Distorting Roundness

I want to change the size of a rectangle width wise from the anchor point I've set (from the left). Not 'scale' but the size property in a rectangle path. I know I can do this with scale property, but this squashed the stroke. 

The only work around I've seen is, using this in the anchor point expression:

w = content("Rectangle 1").content("Rectangle Path 1").size[0]; h = content("Rectangle 1").content("Rectangle Path 1").size[1]; [w/-2, h/-2]

Is there an easier alternative to this? or am I doing this wrong?
Also shouldn't this be the default expected behaviour when setting an anchor point and scaling?