A referendum should not be necessary for the legislature to do the right thing. However, we now have an obstructionist Senate majority, which tends to block any progressive legislation. So in order for "right thing" bills like this to pass citizen referendums probably will be necessary. That is a sad commentary on what is supposed to be a representative democracy.
If the workplace smoking ban goes to a public referendum, chances are it would pass handily, according to current public opinion polling. If that is the only way we can get such legislation on the books, so be it. But we should remember the lesson about obstructionist legislators when it comes time to exercise our term limits power as voters.