Yes, it certainly doesn't take any more effort to make a positive comment.  I think criticality can become a kind of passive-aggressive habit and maybe reflects what's going on inside the one making the comment.  If you get enough of that from your partner, it feels like less hassle just to say nothing rather than risk a "smart" remark.  I grew up in a house like that - it doesn't take long to figure out that there's not much you do that's worth much and that you seem to only have the ability to make people angry.  It's too bad people can't see what effect their words have, usually until either a blow-up occurs or it's too late to save the relationship.  It takes a strong will to not succumb to the negative comments and let them dampen your mood.