A lot of people don't think jazz has the energy that hard rock/metal does. I think it often has more, it just manifests itself in more subtle ways. In metal, it has more "power" because it's loud, it's fast, its distorted, and its angry, that's not an insult, that just tends to be what people are refering to when they talk about metallica having a "heavy, powerful" sound.
Try listening to Giant Steps by John Coltrane. That energy, that power, its there, he's just not playing a distorted guitar, he's playing a tenor sax, so it sounds different.
As for playing jazz, I'm working on it, but its very hard to bull**** your way through. With blues/rock/metal, even if you're not that good, if you know what key you're in you can bull**** you're way through a solo without sounding terrible. It's a lot harder in jazz because there are constant key changes (at least in bebop) and you (usually) have to think about each chord you're soloing over seperately, rather than looking at a song, determining what key its in, and soloing in that key.