I think that's the major diconnect here......the difference in tone is pretty big to my ears, but more importantly the articulation is WAY different. I think both alternate picking and economy picking are both very important things to have at your disposal. Everytime I learn a new lick I'll practice it with both approaches. Even if it's something that should normally be swept (smoke and mirrors intro for example), I'll learn to play it alt. picked. Of course I can't alt. pick it as fast as I can sweep it, but that's besides the point. To me, the difference between economy picking and alternate picking is almost as significant as the distance between alternate picking and hammers/pulls. Try (for example) to play some Steve Morse lines with economy picking and see if you can nail the same accents and articulate the same way he does. You can either try for yourself or just save some time and take my word on this one....it wont happen. On the other hand, try to tackle a Gambale solo with alt. picking. Even if you could alternate pick it up to speed, there's no way you could ever get the same fluid sound he does.
Of course, there's nothing wrong in choosing to economy pick 100% of the time in your own playing if you think that's what will serve you best. Just make sure you're making a decision based on sound rather than what's easiest. I definitely encourage you at least explore the subject though, it certainly couldn't hurt. Then again, you could end up becoming a little over-obsessive about it like some folks would say I am
