I agree that it's not nice to be over critical to fellow artists, but everyone that uploads does have a choice...

*Allow viewers to make comments on this image?

*If one asks for critical comment then one should expect critical comment, however, if one is being over critical by saying 'your art stinks' then thats another matter.
To be honest, I have not seen any comment that might constitute anything that may destroy someones artisitic confidence, but then I have not reviewed all art here at Renderosity.

It would be informative to see the type of comment that you are referring to.

One other point, if only one person gives a 1 and all else give a 5 or 4, then the figure should not deviate very much from the higher scores, or at least thats what i've experienced.