Why couldn't the male mage Inquisitor have the same oufit as Dorian?

All the companions have more style than the Inquisitor, but their gear can actually reflect their class and culture. The Inquisitor's gear has to work for warriors, rogues, and mages, with minor changes, so that probably limits what they could have done.

The Inquisitor also can't have the same style as Iron Bull, Sera, Vivienne, Cassandra or....anyone else really. In addition, the Inquisitor (regardless of race) has their own unique "Inquisitor" style different from that of the companions. An exception being race specific armor like Templar armor or Dalish scout armor.

I can understand wanting to have a "cultural style" option, but for the most part we have:
"Inquisitor Style" + myriad of crafting recipes + armor additions + selective armor bonuses based on materials used + dyes = pretty fleshed out crafting system.

Its more than enough. It's above average actually (just look at Skyrim's/ Witcher III armor crafting). Many games go "Craft X" gear with predetermined stats that cannot be changed unless you go to the next tier and cannot have anything added to it armor wise. The closest you can usually get is enchantments. If you're lucky you can get its color changed.

The amount of choice that goes into crafting in this game is quite frankly unprecedented when in comparison to other games.

Their are mods here.... So.. Who knows?

There's a mod for that. www.nexusmods.com/dragonageinquisition/mods/887/?