Jesus only on HF is a draft pick worth more than a 99 point forward in his prime.
As others mentioned, it's tough to ignore Miller's age/contract situation. Going back to when the Islanders knowingly traded the Jason Spezza pick:
Alexei Yashin's 2000-2001 season: (age 27) 88 points)
And allegedly the Islanders made the same offer to Boston for holdout forward Jason Allison.
Jason Allison's 2000-2001 season: (age 25) 95 points
Both Yashin and Allison were in their primes but required expensive new deals. Their subsequent few seasons:
Yashin
2001-02: 78 GP 75 points
2002-03: 81 GP 65 points
2003-04: 47 GP 34 points
Allison
2001-02: 73 GP 74 points
2002-03: 26 GP 28 points
2003-04: DNP
Admittedly a little unfair since Allison had some major injuries that derailed his career. But I don't think I'm going out on a limb thinking that the Islanders maybe would have rather have kept Spezza long term. Yashin nearly helped them win the division in Year 1 but started to decline thereafter.
I'd also have concerns that Miller's 99 point season will end up looking like an outlier season.
Not to pick on the Islanders, but I'm also reminded of the time they traded a 1st+ for Thomas Vanek who was an impending free agent. Vanek was reasonably productive but declined to sign an extension. Islanders then traded him for less than what they gave up. Vanek left some money on the table by declining the Islanders extension to sign with Minnesota. Vanek should have still been in his prime at age 30 but started declining shortly thereafter.
And I don't think whoever goes #2 this year has the same upside that 2001 Spezza did. But #2 for an impending free agent that'll be looking to cash in seems unlikely. When the Devils were more likely in the #5-8 range in the lottery, it made more sense to flip the pick for somebody who could help immediately.
I'm also reminded of the 2015 Draft when the Sharks nearly traded #9 and a young Tomas Hertl for T.J. Oshie and Kevin Shattenkirk. They got cold feet and decided to keep the pick and take Timo Meier. Shattenkirk likely would have spurned them to sign for less with the Rangers in 2017. How bad would the Sharks have been the last couple years had they done that deal?