Money (and term) will be a massive hang-up
J.T. Miller is under contract until 2030, carrying a cap hit of $8 million annually. He'll be 37 years old by the time the contract expires, making it another bulky contract to take on. Considering the Golden Knights already have Tomas Hertl's deal until 2030 (a $6.75 million cap hit thanks to San Jose retaining 17% of Hertl's salary), it's best to leave the 31-year-old center to go elsewhere.
That's partially why Kelly McCrimmon hesitated to give Jonathan Marchessault a five-year deal. Would you want your team paying both Hertl and Miller until they were in their late 30s? That would hinder the Stanley Cup contention window for short-term gain.
As for Elias Pettersson? Well, he might be five years younger than Miller. However, his cap hit ($11.6 million) is significantly higher. Even with the salary cap jumping to $92.5 next season (and potentially higher afterward), the Vegas Golden Knights must contend with re-signing Jack Eichel.
Sure, the thought of making the Edmonton Oilers change their pants to the brown color with Pettersson/Miller and Eichel sounds enticing. However, it's a move that'll handicap the Golden Knights if they proceed. Given that both Canucks players have lower numbers than last season, it'll be a riskier move.