I found them curiously lacking and what was there unconvincing. The argument against is really that people will take them even if they aren't sick. There are several answers to that. One, is pay them for not taking them. The negative is that costs the employer. But, we could make that a tax credit or deductible expense.
Actually, my argument is that the government does not need to be involved because most companies already have some kind of provision, and many companies are moving beyond "sick time" in ways that are more beneficial to employees. If the government starts mandating sick time, then that will force companies to restructure their PTO options, and prevent them from offering superior options.
Why in the world you would have a problem with that, I cannot understand.