Do I understand correctly, that with this change and on HiDPI displays, Wine windows (defaulting at 96dpi) will appear as small windows by default? This doesn't look very desirable to me?
Also, I don't know how well our DPI code is, but I haven't seen much activity on that side and I would not bet that it's doing super well (the look of winecfg with non-default DPI already gives me a hunch that it's not perfect). So IMO you're going into troubled waters if you want to rely on it.
Still, I don't mind looking at this, but fwiw it feels a bit premature to do this now.