Think "smooth" instead of "in your face".
I attribute this to the large soundstage which tends to be more comfortable to listen to than the treble attack from Grados. They're boring because they do everything well, and they've been out for a while, so people want to buy other things instead now. Other than that, they're still world class cans and among the best I've ever heard. The Sennheiser veil is exaggered as well. It's there, but only as a way to not fatigue your ears over time. The detail and timbre is all there and the bass is definitely real.
That being said, except for the HD800 which I have no experience with, no Senn will match the detail and attack of Grados. They're just too fast due tot he simple nature and the thin mylar membrane of the drivers. You get a lot of bass tradeoff from that unfortunately compared to Senns. Sennheiser needs to make amps though, it's unfortunate that they left that area blank and just have poor people guessing which amps to power these with. Although to be fair if you plug them into a Onkyo/Denon receiver, they do JUST fine.
What you think they're gonna claim that they make the best headphone in the world back in the day at 499 MSRP and not have it appeal to the masses? It's great at everything!