Why glycoproteins are better than non-glycoproteins in fulfilling biological tasks?
The central reasoning is flawed because it places some intrinsic value on glycoprotein modification. The general intuition is that, if the protein is glycosylated, then it's likely for a reason, whether it be to help fulfil antigen recognition, adopt a correct conformation, or help in molecular tethering. Beyond, that, many (perhaps a majority) of cellular proteins are not glycosylated. Two important examples of cell membrane proteins that are not glycosylated would be endoproteases (eg, furin) and chemical transporters.