Yeah, BS really does suck. I am waiting to upgrade it until I get a legendary plan drop or something, and even then, I'd only do it after Blizz fixes how much the legendary crafted items suck. The one weapon that is appealing because if its stats has pretty low dps and costs something like 290k to craft and then, like you said, you still aren't guaranteed to get what you need.
I did invest in JC because commodity auctions have been down for the past 10 days it feels like, and I wanted to upgrade my gems. It does seem like there's a totally broken balance issue in that you can by gems on the AH for cheaper than it costs to craft them with the jeweler -- at least until you get up to the top 2 gems which don't drop from random world mobs and which you need to get plan drops in order to craft with the JC dude.
I did a little reading and it looks like Wizards do derive their spell damage from weapon damage (overall dps, of which weapon damage is a major factor). For always railing against simplification of these games, I actually kind of like the fact that they've done away with the differentiation between types of armor and weapons, i.e., no cloth, leather, mail, etc.