When it comes to variety I personally think less is more.
To elaborate.
I'm straight male so I'll focus on females.
In DAO we have Morrigan and Leliana. They have a lot of similarities. They are both along for no apparent reason, they are both feminine (and femme fatale for that matter), a bit cryptic. Both like to tell you stories. Observing their differences (beyond the obvious) is interesting. Like for example Leliana likes to tell romantic stories while Morrigan prefers to talk about her mother. Morrigan getting offended by Leliana's attempt at educating her in fashion for example which creates another contrast. Morrigan likes shiny things, but what about clothes. Is it that she doesn't care about it, or that she is defensive around Leliana? That's intriguing. Morrigan is quick to bed, Leliana is slow. Another intriguing part. Morrigan, distrustful and antisocial doesn't have many qualms about it while Leliana which is a professional people's person does.
Sure it's not that difficult to figure out the why, but it's interesting to observe.
Also the way they change creates a contrast as well. Morrigan is pragmatic and finds her romantic side. Leliana is romantic and finds her pragmatic side (which you have control over). They don't reach the point of acceptance, but they are well on their way.and it will be interesting to see what happens in DAI.
Another great example is Dawn Star and Silk Fox in Jade Empire. They both care about the greater good, they both care about the protagonist. They both have manners and care about etiquette. Easy to find middle ground.
A bad example is Miranda and Jack. They can't find common ground for this to work.
Then we go on to DA2. This doesn't get reflected at all.
We have Merrill and Isabela. The only common ground they find is that one likes listening to the other's stories about her sexual encounters. I like Isabela's style, but I can't bring myself to care about Merrill. I help her with her clan but that's it. There is no thought process, no comparison. Merrill is totally uninteresting in my eyes.
Don't get me wrong, I'm not saying that this design is bad, it's just not to my liking. I like playing my characters close to myself with variations. I guess this design is better for those that prefer to roleplay totally different characters so they have more options.
What does that mean for DAI? I can't know yet. Being bi or straight, angry or kind doesn't matter but I have a hard time perceive these similarities I describe in the characters shown. Cass and Josephine look like totally different concepts. The only middle ground is Vivienne and it's not confirmed for LI yet. I can see Cass+Viv and Viv+Josephine. Essentially if Vivienne turns out not to be a LI, I don't see myself caring about Cassandra at all. The DA2 Cass could work, but the new one doesn't, unless her character is different in the game than the trailers.