I think we should aim for mandatory doping, it'd certainly be entertaining.
It's a process of thought. Why do you think doping is bad? Is it because its cheating? What counts as cheating exactly? Are some forms of "cheating" worse than others?
All these questions must be answered.
For instance, a lot of people have said certain swimsuits were cheating because they were far too hydrodynamic (right word ?). I won't post a picture in case i offend anyone with modest sensibilities but they were very fitting if i recall. They actually did speed people up but do they count as cheating? Eventually they were banned for the record.
Same with runners. The original Olympians didn't have sports clothes. This is because sports, as recreation, wasn't really a concern for 99% of the population who had to work from almost dawn to dusk, especially in a competitive sense. They ran in their normal, daily street clothes (more or less), including regular shoes. To those people, our runners of today would perhaps be cheating as well. The original marathons were racked by scandals including people doing part of them by horse (hard to monitor back then).
(Note their outfits; original Olympic marathon - 1896) I think anyone caught doping should at least lose any achievement derived from it. I think for serious doping, serious sanctions are needed. It should be assessed on a case by case basis. For individuals under immense pressure with a lack of history of doping, i think they deserve a second chance. For a serious, orchestrated and planned regimen, especially one that shows little chance of going away, then perhaps a total ban is warranted.
It should also depend on how much of an edge the drug(s) gave them and just how wildly they flouted the rules (loophole or smack in the face?). Some attempts at doping give only a very modest edge (based on the drug(s) used), others would be massive.