Yes, the merchants in Diablo 3 are consistent with the ones in D1 and D2 which is to say that they are useless. Perhaps the one exception being the ring and amulet vendor in Act 1 because you can generally get one from that vendor prior to one dropping for you. Squirt, in Act 2, sells the Hellfire Ring and Hellfire Amulet plans for 2 million and 4 million (respectively). The biggest money sink goes to gem upgrades at level 70. Going from Marquise gems to Flawless Royal will cost you 81 Marquise, 9.8 million gold and 4 death's breaths. Upgrading gems you leave you broke...trust me...
I guess I've upgraded to whenever you need the first death's breath or whatever... whenever it switches from just needing money to actually needing stuff. I don't have the stuff and as far as I know can't buy it so for now at least I'm "done" and have tons of money left. It just seems to me at this point at least the limiting factor is the stuff not gold.
Mind you, the axe with high int on a Wizard may still be a good weapon. Wands and Sources have a chance at some wizard specific stats and tend to be much faster cast speeds which make them more desirable (if the other stats are good).
I guess that's our problem with wanting things to fit in a role-playing perspective more than just min-maxing stats. Maybe some of those axes would have been great for a Wizard but she just doesn't want to run around with dual handed axe wielding wizard.
On consoles at least they put a lot of effort into coop play though with 4 player local coop, nemesis generation, legendary gifts, and such but the tailoring of drops to your character works against that. She's not going to use a bow, crossbow, or hand crossbow on her wizard but she occasionally gets them. My Demon Hunter would love to use them but the fact the game keeps slapping INT bonuses on them really hurts that if she wanted to give it to me. Even besides giving it to me if she wanted to make a Demon Hunter character later and use the sweet Legendary Bow she got it's sabataged by the stupid INT bonus instead of DEX. The Armor works fine because I think anyone can use most of them and they just look different depending on which class equips them. But certain weapons/shields seem tailored to a specific class or pair of classes featuring the same attribute preference so it seems like it would have made more since to restrict those items to those attributes with VIT being the catch all. If you really want to play a Wizard with an Axe then even if Axes couldn't get INT bonuses you'd just look for one with VIT instead since that applies to any class. Anyway we're still having a blast playing the game. I'm not sure I'll be spending a ton more time playing it solo but it really is fun sitting on the couch playing coop with the gf on the living room TV.