But until the day that monitor resolutions become equal to or exceed printing resolutions you will have to choose between "ease of use" and "quality of output".
I can't really see what easy of use has to do with quality of output. LyX does both (well, it is not as easy to use as Word yet).
Anyway I think the answer is simpler than yours ....
We can do fancy graphics things now a days to make pictures/text on screen look much more like their printed counter parts (anti-aliasing blah blah). So I don't think that a WYSIWYG requirement will screw up your typesetting. I suppose strictly there is a compromise but I think the difference is minor.
Also if you take a look at PDF files say, generated from TeX output, and compare them to equivalent files generated from Word .doc files, you can still see the difference in typesetting. So the limitation isn't the monitor or a WYSIWYG requirement.
I think the simplest answer for difference of quality is that most word processors use bad typesetting. Either because they came up with typesetting algorithms, or some sort of performance consideration[1].
Marc
[1] I guess this is also a "limitation of computer hardware" argument. But I don't think the limitation is screen resolution, rather processing power. I imagine a WYSIWYG editor that also produced good typesetting would be a huge resource hog.
