Just as well, I might cut myself! '
'Sharp' is a bit subjective. - It's rather off topic, but I am inclined to agree with you, up to a not particularly 'sharp' point.. which hinges on the 'importance' of this 'sharpness' every-one puts so much store by.
Kit 18-55.. no.. it's not, by quite a long stretch a fantastic high grade lens. But, its far from a 'Bad' lens. By definition of 'quality' being fitness for purpose, rather than any specific and potentially redundant 'excellence', its actually a very 'good quality' bit of kit. An Aston Martin is a very good car but, it's no better for going to the shops than my Honda Civic, while neither will do my shopping for me!
Shipping with the camera body, and retailing with it as a 'kit' often cheaper than the body-only, it's almost a 'free' lens, so damned good value for money. It covers an incredibly useful range of focal lengths around the 'normal' angle of view. It's acceptably 'fast' at f3.5/5.6, has a fairly good close focus, and it's optically pretty 'reasonable' for most situations. And for expected users, it's actually very very well tailored and few are going to be let down by it, and learning to 'look', ought be able to get a lot of very good photo's with it, that a 'higher grade' lens wont get for them, or make much if any 'better', if they do.
Nikon, upping the game in their sensors, I think have probably run ahead of their 'kit' lenses a little, and it's not that the 18-55 is 'poor' just not as good as the 24Mpix+ sensors used in cameras developed since they designed it. I have 24Mpix D3200, my daughter has 16Mpix D3100. Both shipped with the 18-55, and for the most part the lens is pretty darn good, and a 'newby' buying an entry level DSLR is unlikely to be disappointed by it or notice any particular 'fault', especially without anything else to compare it to.
I do, and using 'legacy' M42 screw primes lenses on either camera...yeah... there's a 'difference'. It's not obvious, and a little less so on the lower sensor-res D3100. Daughter has the 'hobby' f1.8 35 & 50's for her camera, and intriguing to compare them to using my Pentacon 29 and Zeiss 50 Legacy lenses, as well as kit 18-55 covering the same rage.. Still a 'difference', but particularly used at wider f-stops, it's not really 'sharpness' or lack-of that is being shown up, apertures wider than f3.5 reducing Depth of Field and softening the image anyway. You have to be shooting over about f8 and at longer subject distances to get front-to-back sharpness across the frame where it might, at quite significant pixel peeping magnification be observed. And THEN, I am not convinced that what is perceived as 'sharpness' by many, is actually the optics of the lens and the size of the circles of confusion rendering small detail in the scene, so much as digital processing sampling the tones and making a 'harder' cut-off between levels, creating more clinical 'contrast' , generating an 'illusion' of sharpness from dumping detail and 'subtlety' in tonal rendition. And so the subject and lighting is likely to as often to be responsible for whether we 'see' a picture as 'sharp' or not, as the lens or f-stop.
Meanwhile, I said that sharpness is subjective. Regardless of what it is that's delivering this 'sharpness', do we actually WANT it? Does it really make photo's 'better'? Like said, what we perceive as sharpness, I think is as often as not a lack of tonal subtlety, a contrast reduction making the image more clinical, harsher and colder. We didn't have this obsession about 'sharpness' when all we had was film, and rendering of silver halide was inherently that much more subtle and less 'sharp', and folk praised slow film or for that subtlety or different emulsions for the 'warmth' of skin-tones they rendered, or the colour saturation they delivered, irrespective of the grade of optics that put them there!
