Of course not. Would you trade a 1st and a 3rd for 28 year old Chris Kreider?
Miller at 26 is perfectly fine for Vancouver if they start to complete in the next two years. But if they sputter for two more years Miller will be two years older and two years closer to UFA status. Miller is a valuable piece, I agree. And if this pushes the Canucks into the playoffs in the next year it'll be draft picks well spent (and the biased Canuck fan in me believes this trade will be worth it). However, if the Canucks don't make the post season the next two years and have to give up a lottery pick, well, those have the potential to be way more valuable than a 28 year old player and Benning should've waited (in hindsight) to make a trade like this.
Time will tell, I think it'll work out for the Canucks (meaning they make the playoffs this year or next) but it's not a slam dunk.