As with any fan's opinions on a player, that is 'to each his or her own thing'. I understand why an outsider would feel as you do, given maybe you only see him play a handful of games. From his first preseason game vs the Leafs in 9/2011, I've not been a fan. To his credit, he is a very physical player, a big body that hits (although borderline dirty, during last year's playoffs, glenn healy made a video on the Canadian feed, thru the first 5 games of how many times he got away with it, 'leap and lead Schenn', leaps off his skates, leads with an elbow. )
His role on wing will be replaced and on the PP.
Most of his points come from playing with Giroux (38 out Schenn's 59 last yr, came in the last 39 games when he was with Giroux and on the PP, same as Hartnell's 37 goals the yr he played with him. Giroux draws coverage and there is usually an open space around the net)left to his own devices, he can't create much. And more importantly, he was playing for a contract. That 3 and a half months (which one article /analytic s observer noted with charts had an 'unsustainable high shooting %, something that would be very difficult to repeat) doesn't equate the prior 4 and half years.
His play in his own end, poor decision making, turnover machine, etc, won't be missed at all. He's inconsistent for long stretches, lazy too often and lacks the wherewithal to elevate his game in critical times for the most part. WAy too many SOG's, zone time and scoring ops such when he's in his own end. That's lack of IQ and instinct and has not changed in his 5 yrs here. And too many dirty hits.
The FLyers have forwards that can take his place, esp since Hasktol's system is suited to that. Konecky is a far more skilled player and will easily take his place on the PP. Raffl is always good with Giroux. They have 3 lines that drive the play and can create offense.
But there are others love him for the hitting and the body part goals. So it's just a matter of what you like in a player.