I don't know Sessions or have an opinion about him one way or another. I do know that nobody is perfect and that none of Trump's appointees will be perfect, either.
The old saying that you can't please everyone applies here.
I live in Washington and many of the municipalities have embraced marijuana because it provide something to be taxed.
Never mind the social problems that it causes.
Now, at night, the wife and I don't like to be out because not only does one deal with alcohol impaired drivers, but with ones that are 'high' as well.
Furthermore, since legalization of marijuana is still relatively new, the social ramifications have yet to be blatantly apparent. But, they will surely appear.
No more than before, since people responsible enough to avoid pot when it was illegal will be responsible enough to avoid driving under its influence when it's legal.