I'm sorry, but dungeons, mini-dungeons, JPs and two of four structures in WvW is a pretty wide range of activities for a material type. I mentioned I'm pretty casual, but I get in a dungeon or two a week, maybe a JP if it's a daily, and a little WvW every Friday night. It doesn't feel narrow to me, and unlike Ascended gear being limited only to Fractals, this method touches on just about every aspect of the game, and where it doesn't the other material types do.
Honestly, if you're just out killing champs, doing JPs and playing the game like you normally would, you're going to be getting these materials. If you want to farm them, you don't even have to do the same thing or stay in the same area repeatedly to do so. The presence of these new rewards may also encourage people to try something they don't usually do (but not so narrow that they have to do something they dislike). I really don't see the problem here.
Also, where this any other MMO, it would be "Please Raid or fuck off, thank you."