Dwarven Characters are short. They are isolated culturally. Majority of Surface Dwarves aren't warriors. Dwarves can't be Mages. And Bioware tends to try and even out classes a bit after DA:O
So Dwarves, being limited in class possibility alongside their stature makes difficult for animations LI-wise have been poorly represented in some regards. Orzammar was an absolutely astounding place and they showed politics and intrigue. But the companions have been lacking to generate interest in Dwarves.
Oghren is a drunk, farting, belching machine. Sure he's likely alcoholic because of how his honor has been taken from, his wife became a villainous monster and cheated on him, and people make fun of him on the streets. But he's lewd, disgusting, has a vulgar sense of humor, and the rare times he sobers up are far and in-between. Then his family problems when he joins the Grey Wardens only go to show he hasn't reformed with the Warden's help, and left his child behind. He's not a good representative of Dwarves at all. Plus according to the level design, Orzammar is the last place to go before the Landsmeet and Oghren only officially opens up after Orzammar. Not alot of time for players to even get to earn his sobered-up scenes, let alone care. Any depth he has is mostly lost in Awakening.
Sigrun is a nicer step towards Dwarven culture. Legion of the Dead. Wants to die. Has past mistakes to amend for and shows the Carta's influence if players don't encounter the bug stopping her quest from playing. Which in most cases happens. She's perky and has incredible spirit but her small involvement and pressing events don't let us really delve into knowing our Awakening companions really well.
Varric is a Surface Dwarf. He's with Hawke no matter what, and can't be sent off. He's popular, and has alot of sway. Kind, charismatic, has a good sense of humor (although it's not perfect), and compelling. He's his own character, but his dwarven aspects are there and are on display. He's got the potential to be a Garrus-like character in terms of popularity and being the only Dwarven companion in the Inquistion, his people are going to rely on him for representation.
If I had to ask for a new Dwarven companion...a Noble would be as fun route. But not one bent on revenge like Sebastian, Cousland, Howe. Maybe they want revenge, but it's not a driving focus. I feel like that direction would be a step forward for Dwarves.