Indeed sharpness is must in image. After using friend's 18-200 for couple of days at a wedding I started feeling jealous as I did not have that reach in any of my lenses. But when I shifted to my 50mm 1.8 on the third day. 18-200 was just a extra luggage and overweight in my bag.
Having said that sharpness is relative I think. Average sharp imge that has amazing bokeh looks better to me than the image with everything in 100% sharp.