Technically Obama was saying "I get to choose what laws the feds follow" with the stroke of my pen. To me that sounds
more authoritative than what Sessions did here by revoking such an act.
I'm all for state rights, but I personally see overreach in executive power as the far bigger problem of the modern era. Executive power exploded under Obama (a trend which Bush started before him, which Obama took much farther).
Ultimately the real problem is that congress needs to end prohibition via law.
Obama basically took a 'sanctuary city' approach, a "workaround" and not a solution to this problem. Which ultimately still left the law very much up in the air for many people in states running weed businesses. I hate the fact people are going to jail for marijuana but I do see an argument here that Session's change:
a) incentivizes congress to put a proper policy together, where before it was left in legal/political limbo
b) ended a bad law which typified executive power overreach
c) is not yet clear how it will affect states in practice, as it's still up to the state attorneys to act on it
In practice this sucks, but I don't think this sucks because it's an extension of government overrearch.