In my professional opinion as a Flyers fan, longtime Pittsburgh resident, and decently well travelled hockey fan, it's unfortunate.
The ticket prices suck, but the Flyers had comparable ticket prices up until the rough patch they hit recently. The Wellschoviastatesunion Center is 15 years older and a bit more compact in construction, but the fanbase, wealthy or not, buys into the reputation. It's more "family-friendly" than its early years and certainly the Spectrum, but it's not even close to a tame atmosphere. With the dark red seats and the low lighting and the shocks of orange all over, it creates some of its own imposing atmosphere, and the drunk unrulies finish the job.
The consol, on the other hand, has beautiful sitelines and is bright and full of light colors. It feels more laboratory than coliseum, really, and that's a bad starting point. The fans also seem unsure how to act. I honestly think it's a lack of knowledge of the game. Obviously there's tons of tuned-in old school hockey fans at the CEC, but there are just as many, if not more, brand new fans who bought a shirt in 2009 and learned a few names the next season.
It isn't so much yelling and cheering, it's breathing the game and reacting to it. The most astounding thing about seeing a game in Montreal is realizing there's 20,000+ fans as knowledgeable and understanding as you, tensing up and sighing relief in unison. Of course they cheer way loud and chant some stuff (Olè is stupid) but moreso than that, they're groaning collectively at offside calls and "Ah-ha"ing at the same time when a player makes a nifty, unexpected pass. That's a good hockey crowd. Philadelphia has a lot of that and also a whole lot of vulgar screaming, Nashville, believe it or not, has a lot of that collective pulse, and the games I saw at the Igloo were good for it.
Consol will get better as these newer attendees begin to get a more natural feel for the game, but Greiss is right-it's bizarrely stale in that room. A combination of the crowd and the space. Drop the lights a notch or two, throw some darker shades in there, switch back to that classic yellow and get that color buzzing in the room. It'll come along, and in 35 years our children will be complaining that the new PNCGoogleDome just doesn't have that great atmosphere of the old Coal Hole.