Baseball has taken a hard line on performance enhancing drugs (though it certainly took them long enough). Football still treats steroid use as an open secret that is necessary to the functioning of the game. How can you tell children in high school that they should not be using performance enhancing drugs when professionals at the highest level are using them without repercussions?
Sports is big business. It is no wonder that some athletes will seek to gain an upper hand by consuming banned performance enhancing substances. This action creates a climate where if it is known or suspected that others are using these substances others will feel compelled to do the same just to stay competitive. The way to combat this is with stiff penalties.
Yes, professional athletes should have stricter sanctions imposed for illegal drug use. Athletes are role models to children, and allowing them to get away with drug use with just a slap on the wrist sends a bad message to the kids that look up to them. Criminal charges should be filed in addition to sport sanctions.
I believe it is up to leagues to decide what should be done to professional athletes who use illegal drugs. For the most part I think they take care of this problem without much attention. I do not believe they need stricter sanctions, if what they have in place now, is working.