Whoa..this is a completely untrue statement. Every time you resize to a smaller size a considerable amount you need to sharpen your image again either using unsharp mask (the noobs way, which sucks), HP Mask with selective masking (the intermediate way) or using the Separation of spatial frequency data method (best way I know). Just using bicubic sharper as an option while reducing will not be sufficient. You can use the best camera and best lens in the world and you still need to sharpen the image, ask any good image retoucher and he/she will confirm what I am saying here.
The default way which PS resize is WITH sharpening. Bibcubic sharpening (best for reduction). Remember i stated for the WEB.
For output i always sharpen accordingly, or for larger reproductions the printhouse do it. I had clients made 10x3meter canvas of a 12MP file which of course was handled by the printhouse.
As for your NEED, as its been stated its very subjective. But for web (800x600 px) a highres image resized with bicubic sharperning will be plenty sharp for prensentation on the web. Now you can add sharpening with whatever method you want some better some worse you will still run at the risk of introducing halos. Sure some of you like the the sharper look with hard edges , i dont.
Ask any PHOTOGRAPHER who dont have time using selective sharpening,blurring backgrounds or pop eye action and dont want to oversharpen their image to look "i have digital camera" and they will confirm what im saying here....
When it comes to camera and lenses, they certainly play a big role in the appearance of sharpness and micro contrast thats affect it.





