Assigning fault is very hard in comics. Sometimes it's easier for me to just say what I like and don't like.
E.g. I strongly disliked the new direction DC took Cassandra Cain post-OYL. And, I am overall very happy with Cassandra Cain's return to DC canon. No one can debate or question these personal statements I made, unless they're Martian Manhunter or Professor X. No doubt not everyone will agree with them, but that's fine, different strokes for different folks.
Apply this to Dick's role in BRE:
[user X] says: I'm unhappy that Dick isn't more prominently featured in a weekly titled Batman and Robin Eternal when Dick was the original dang Robin!
[user Y] says: I think the panel time and story threading for the BRE characters is fine though some (or one) character might shine more for other reasons than writing.
Specifically, I see Cassandra Cain as a more extreme and strangely faceted character than Dick Grayson. That's *my* opinion and I'm not claiming she's better or worse. I do enjoy her more but that's just me.
I'm not super up on his background but I think Dick was pretty well adjusted before his parent's were murdered and he had a fantastic youth up to then as a circus acrobat. After the murder he was adopted by a super rich guy who happened to be a super crime fighter! How great is that?! And Bruce took him on missions and trained the heck out of Dick.
Fast forward to today and Dick seems to be the most mature and well balanced Robin. He can hold a conversation on "work" about tracking down and defeating bad guys plus he can have a coffee or beer and talk sports or current events. He can (does?) date and has friends. He's a Catwoman level acrobat, a very good fighter, a superb detective, and is excellent at using technology. He negatives are his parents were murdered and now with BRE we see there are Batman job confidence/heir issues.
How about the new Cass Cain? Well, her traumatic childhood is so extreme it shouldn't be called childhood. Maybe "ongoing, hyper-abusive psychological and physical torture" would be more apt but that's a mouthful! Cass at 16 is a tier1 fighter IMO and could probably at least hang with Batman. While David Cain doesn't get much fighting respect on this forum I think he's a great fighter and she can hang with him. Cass is at least a decent acrobat, can use a grappling gun, and throw a dagger well. She also has some level of non-fighting skills cause she somehow got the Argus jet to fly over the mega-pit.
Does Cass have negatives? OMG yes! Dick (and Bruce for that matter) had his parents murdered in front of him... and that's it! Cass doesn't know who her mother even is and her father is a titanic parental monster. Not to mention David Cain is a mass murderer, probably in the hundreds. Cass is haunted by her (at least one) execution of a woman in Gotham (Harp's mom?). She's already demonstrated PTSD when Harper touched her hair in a non-stressful situation. And Cass probably has PTSD from her youth: being made to watch the bloody execution of dozens or 100+ people by your father as a little kid? Unbelievable.
Cass can't hold a normal conversation. At all. With anyone. About anything. She's said Mother 3 times, Where once, Children twice, and No. That's it in 13 issues. It's very, very likely she can't read any language, not even Najahoe! She has *no* social experience before she fled her father and thus almost no social skills. Talk about sports? She probably doesn't even know what sports are! Not to mention she can barely speak at all. In fact, thought it's not explained yet, I don't think new Cass even *thinks* with language like other comics characters and we do IRL. She likely sees shapes, motion, expressions and thinks in that way.
These are 2 very different people and they're gonna "shine" differently that's for sure. And this is in the eye of the beholder.
But I feel that Cass has a lot of extreme stuff in her makeup, much more than Dick who I like. But Cass Cain popping more than Dick for some readers isn't surprising for me and I don't think it necessarily anyone's "fault." Cass is a child of 1999 and 2015 while Dick is from 1940. Everything is more "extreme" now though I'd argue that Cass has the most extreme background of any Batfam member, ever.
But that's my opinion and others will think otherwise. And some may think that she's the most extreme but that's no reason she should dominate BRE. I don't think that but different strokes.
PS - I'm loving BRE! This despite some weird art making the Robins look the same, Steph being MIA, and Cass being gut-kicked then candlesticked then held/gut-punched. These are small complaints compared with the overall treatment of Cass' return (best New52 treatment by far for me), the Az intro, most of the flashbacks, Jason has had nice moments, and I'm digging Dick as the mature leader of this motley Batfam crew trying to follow their MIA leaders orders.