I believe that in Canada low vis ops are a required part of recurrent training. Admittedly, it's only a few questions on a written test, usually administered in the spring. Maybe an IFR requirement wouldn't be a bad thing...
In Helicopters Mag issue #2/2001 (Canadian publication:
www.helicoptersmagazine.com) there's an excellent article on low vis training. It's a good read for this (or any) time of year.
Can we be trusted to know and respect legal vis limits, or do we need to have more legislation? Since the CPL is already a legal, skills-and-knowledge certification, adding IFR for snowy conditions isn't a conceptual quantum leap. But it still wouldn't mitigate the issue of customer pressure to complete the mission. None of my LZs have an instrument approach, so an IFR rating and radar alt would help me avoid CFIT, but won't help me reach my destination.
The real point of such legislation must be to ensure that we can turn around after inadvertent flight into IMC. Fair enough. Keeping the skills sharp during a season of (primarily) VMC is another question. As is getting every friggin helicopter in Canada outfitted with a radar alt! Bet there'll be some operator resistance the that one!!