Those "benefits package" can be pretty freaking lacking if there isn't a government-mandated minimum. You'll be stuck working for a company that has the upper hand in negotiations and you'll get a shit deal. Unless you're a particularly attractive and sought after employee (which most people aren't), you won't get anything above what is considered the industry standard at the time, and the industry standard may be pretty lacking.

Those laws exist so that people aren't completely fucked whenever they happen to get ill, or that they are actually able to enjoy life, relax, etc. If that's not what you want and work anyway, in most jurisdictions, you can work overtime, get a new contract, get an extra job etc. The only difference here is that the employer can't force or coerce you to work in those circumtances.