As best I can tell, it's widely believed by those on the right that Sessions is the reason cannabis has not been rescheduled during Trump's term so far. With him gone, it seems very likely to happen. If it does, I expect that he will easily be reelected.
Also, combined with Trump's recent tweets re: investigations, I expect we're about to see all sorts of fireworks by both sides.
That’s not at all why this is a big deal. Sessions recused himself from overseeing the special counsel. Rod Rosenstein, the deputy attorney general, has been conducting honest and principled oversight to the dismay of republicans. Now that Sessions is gone, Trump can appoint a sycophant to undermine the investigation. This is terrible news for our democracy and the rule of law.
From a purely bi-partisan viewpoint, I think this is a big deal for many other reasons as well. If I remember correctly, a few Republicans defended Sessions saying that his firing would cause some backlash. This was due in part for their admiration of the man as he gave up a Senate seat to become AG and for being a pretty staunch Republican. On the left, Sessions is known to be the leader of all the big police/drug/immigration policies that the Trump Administration wanted enforced. He also was a piece of the puzzle between Trump himself and Mueller like you stated above. His ousting definitely has feathers ruffled on both sides from what I can see.
As best I can tell, it's widely believed by those on the right that Sessions is the reason cannabis has not been rescheduled during Trump's term so far. With him gone, it seems very likely to happen. If it does, I expect that he will easily be reelected.
Also, combined with Trump's recent tweets re: investigations, I expect we're about to see all sorts of fireworks by both sides.