The MorphOS look that you see most often is much like Linux in the late 90s or what Windows tried to copy with XP. But it doesn´t stop at the color of the titlebars being in bad taste and icons being autoarranged to weird grids.
The original Amiga OS had to concentrate on the essentials. There was much thought going into details. Icons looked the way they looked, because one found that the image
a) represented the idea best
b) was visible an clear on every monitor by people with moderate eyesight
Todays criteria seem to be: its coooler! It´s mooore!
And the old Workbench had some pretty cool bells and whistles: Many people for example forgot that it was normal to select more than one menu item in one swoop. AmigaOS still does that and if you know the trick it can become more useful than Apples "Expose" or "Spaces".
MUI has a lot of eyecandy and unfortunately is helping you to create interfaces with more buttons than your user really wants. If you really think about how the software is used you will find that less is almost always more.
So I don´t agree with people who are calling the old Workbench-look crappy. AROS in fact does a good job in maintaining the clean lines of the former design.