FAR 91.157 Operating in icing conditions

I KNOW this is a big can of worms, but I have a specific question 
relating to sub-paragraphs b.1 and b.2 of this regulation regarinding 
operating in icing conditions.

It says "...no pilot may fly--
(1) Under IFR into konwn or forecast moderate icing conditions; or
(2) Under VFR into known light or moderate icing conditions..."

This seems odd.  Why do you suppose the standards are different for IFR 
and VFR ("moderate" vs "light or moderate)?  Icing affects a pilots 
ability to control the aircraft, so I do not see how instrument training 
allows one to venture into worse conditions.

So, if there is an airmet for "light icing", then it is legal for an IFR 
pilot to enter the clouds (of course, on a valid IFR flight plan)?

What perectnage of the time, during winter, do icing forecasts get 
issued whenever there are IFR conditions?  In other words, in y'alls 
experience, if you get 100 briefings during the winter time that include 
IFR conditions, what perecntage of those will also have icing forecast. 
 My intuition says that it will be upwards of 90-100% (I am a 
relatively new IFR pilot, so I do not have the experience base to 
say...looking for other opinions here).  If it is close to 100%, should 
I just hang up my IFR certificate from Sept to May (I live in Wisconsin, 
so we only have about 30 minutes of summer here per year :)).

-Sami