I think it's just the way the assessment is being phrased. In short being tactful.
there are many ways to put across a message.
from 'ah beng, you are very lazy. pls put in more effort'
to 'ah beng, i believe you can improve on your result. pls put in more effort'.
as humans, (applies to kids also), we have different reactions to assessment on ourselves. But in general, people tend to turn defensive when harsh direct words are being put forth. that's when we start to loose our rational judgment and become denial to our shortcomings.
so i would say, the society has changed and that harsh word are a thing of past. i mean now we dun see hooligan roaming the streets collecting protection money. generally, the standard of communication has progresses due to the fact the society is better educated now.
therefore, it is natural that such harsh and direct comments are less common now.