It is a little easier to forecast rain vs. snow, but the main reason is because of persons tollerances of the forecast.
Most forecasts call for rain and folks just look for it to rain (or not). They typically do not put much concern into how much rain will fall and most forecasts do not get into the details of how much rain will fall. Thus, a forecast will call for rain and most folks will only pay attent to if it rains or not and not pay attention or care if .10" fall or .75" fall (hence the way you said: we always seem to get the rain, not "we seem to get as much rain as they predict").
Now take that same scenario and switch it to snow. .10" of liquid equivalent snow would be an inch or two in most cases, maybe as much as 3-4" if it is very cold and the snow really fluffs up. .75" of liquid equivalent snow could be as much as 7-10" of snow or maybe even as much as 15" if it is cold and the snow is really fluffed.
I dare anyone to not notice the difference between 1-2" of snow and 7-10" of snow!
When looking at a storm, the models really do not struggle any more with precip that will be snow vs. precip that will be rain. Same level of errors. It is mainly that the errors with snow are much more noticeable.
So I guess in a nutshell it is the perception of the forecast error, rather than the actual forecast error that makes the difference between a rain and snow forecast.
-John