Why not?
I agree with you point but not with your premises, the only people going to jail for 5 years are the ones cultivating or selling large quantities.
With some in the pot debate its about the freedom to do what they want and I can accept that libertarian argument, however with a lot of people its really about making easy money.
Decriminalization is the worst of all choices because it keeps intact the criminal profits and the associated crime that accompanies it. Make no mistake good people and bad are killed over pot money every day.
Legalize and regularize it or keep it illegal. IMO a wink and nod approach would only further enrich the drug traders and lead to further crime.