I suspect he's maybe not a popular locker room guy or something, because his on ice play suggests he's worth way more than he consistently earns.
Dude is a dynamic shooting threat that can create on his own, exactly what you want in a depth scoring winger.
There's always been rumors that seem to dog him wherever he goes, right back through Jrs about having a bit of an "entitled attitude" and "selfishness" that i could certainly see teammates not being all that fond of.
But i think the bigger factor is ultimately just that...Teams typically don't like their "depth wingers" to be of the defensive liability "scoring winger" offensive-minded variety. They tend to prefer guys who can chip in a bit, but primarily just not be a huge liability that causes headaches in the matchup game trying to shelter at all costs. Guys who can contribute defensively,
without the puck, as well as on the PK for instance, or in bringing some real energy and physicality and grit in their limited minutes. To make an impact that way, and let the better, more well-rounded Top-6/9 Forwards handle more of the productive element.
Coaches like "low maintenance" depth forwards for a reason. In that it allows them to focus their gameplan and bench management around their best players, rather than a depth guy that they're trying to play peekaboo with against opposing 4th lines/3rd pairs vs Top Scorers. It just takes away leverage and ties one hand behind the coaches back, when their deathly afraid of their "depth scoring winger" getting caught out there against an opposing top line.