The difference between 30,000 bulk cards from Alpha through Mirrodin and 30,000 bulk cards from Magic 2010 through Khans of Tarkir is hundreds possibly thousands of dollars, so being able to evaluate the collection in person is extremely valuable
As it turns out, for Magics design team, having a potential villain in the room also seems to make games a bit better especially in a biodome, which is what Wizards calls the environment where a release of preconstructed decks are played against one another
You can even turn cantrips like Opt and Consider into hyper-discounted Divinations
On top of that, Narset gives all your creatures prowess, so every spell you cast makes your team hit harder, meaning you can chain removal, card draw, or even extra combat spells right out of the graveyard while buffing your board