Let's not loose sight of the "big picture" here! Most of today's digital keyboards make VERY good sounds. Some make EXCEPTIONAL sounds. If you are very fussy about particulars - there are ways to interface different pieces of gear together to get a "custom" sound that suits you.
I don't expect an "all in one" unit to be superb on all levels. That's not gonna happen, but for working players, like me - the new digital arrangers, and synths offer a portable, versitile way to take my muis to the people that want to pay for it. No one ever says..."Do you have a darker trumpet sound" ??????? The sounds are very acceptable in almost all areas, and absoulutly stellar in some.