The problem is that the Supreme Court has expanded the federal government's "interstate commerce" power to include anything with even the most tangential effect on interstate commerce. Once you decide that growing food at home for your own consumption affects interstate commerce then every human activity affects interstate commerce.
I would love to see some conservatives and libertarians in Congress use the marijuana issue to push through a 10th Amendment restoration act. No federal law based on interstate commerce should apply unless it involves actual interstate commerce.
If you grow, buy or sell marijuana across state lines, then you are subject to federal marijuana laws. If you grow, buy and sell marijuana entirely within one state, then it should be entirely up to that state whether or not to prohibit or regulate it.
Similarly, if an endangered species is migratory or located in multiple states, then killing it is subject to federal laws. If a salamander or bug is located in only one state, then whether it lives or dies has no affect whatsoever on interstate commerce and should be subject only to state laws.
If you want to pollute, dam or divert water from a river that flows through more than one state, then it affects interstate commerce. If you want to drain a pond or swamp on your own property, the federal government should have absolutely no say in the matter.
The list is endless.
And in the case of the various State laws on pot, Gonzalez v. Raich, as noted here.
But my comment is about what should be. We know what "is" due to New Deal overreach.
But being Conservative in the American sense should mean trying to undo all those "Progressive" era usurpations.