"Nice and" expression question.

[JLyon]

My take is that it is very idiomatic.
A sweater/jumper that is nice and warm means that it feels nice  
against the skin and keeps one warm. It also implies that one doesn't  
get so hot in it that one wants to rip the damn thing off to cool  
down. It is warm and it is nice.
Nice and supple implies that it not only is supple but also feels  
nice. It is not a limp piece of cooked pasta, but it is responsive to  
one's actions.
A woman who is nice and plumb is over-weight, but she is still  
pleasing to look at and is not grossly fat. One would say "she could  
lose weight, but I wouldn't bring it up..."
Thus, the "nice and" implies that it not only has a certain  
characteristic, but it is nice/pleasurable/not carried to excess/ 
pleasing/precise.