There are plenty of the reasons why Binary Domain was a dud, Sega's standard complete lack of marketing being the main one, but the biggest reason of such is really the simplest one. It wasn't that good of a game. Gameplay wise, it was a cardboard bland third person cover shooter that took no risks and merely ripped off the standard gameplay you'd expect from TPS at the time. And with a focus on character relationships through simplistic dialogue options, coupled with a Sci fi setting that takes itself seriously enough to the point of laying down a pretty detailed background, despite a pretty lame art direction. Not exactly something that's going to sync with the casual shooting fan. Considering how Yakuza Dead Souls turned out, it's pretty easy to see that Yakuza's team expertise is arcade-ish brawling gameplay, not shooters.
Which is a shame because I actually think it has plenty of potential to become a *REALLY* good game. If they compared Binary Domain shooting gameplay and compared them side by side to Yakuza's fluid, fast paced combat, they would easily see how stifled, slow and bland Binary Domain controls. They should play the TPS in the market that are hauled in the community for their gameplay like the Max Payne series, Vanquish, MDK, Red Dead Redemption, Stranglehold or even Resident Evil 4,5 and 6. Hell, Dynamite Cop or Space Harrier would be great references.
If they combined responsive, more fast pace and arcade like gameplay to the already immensely satisfying feeling of turning a robot into a piece of scrap metal, it would be a fucking great game. As it stands, the palpable physicality of a mechanical target being shot is the best part of the game. Which is why the bosses tend to be pretty great too, when they're not filled with gimmick sections that have nothing to do with actual shooting. And the characters weren't half as boring as they looked, the conversations are pretty entertaining and the relationships that build up really make you feel for these guys, especially when they can barely stand each other in the beginning. Cain is the best character in the game, by the way. Fight me if you disagree.
Spec Ops : The Line's gameplay was deliberately average so that it can disguise itself as a Modern Military Shooter for the story's sake.
http://youtu.be/wlBrenhzMZI
http://youtu.be/Ez0VXCyIShE
Now, I love Spec Ops: The Line for what it is and what it does but that's the most half assed, convenient bullshit excuse for standard, below average gameplay. If the developers (Who never developed a TPS before, by the way) really wanted to disguise the game as a generic FUCK YEAH AMERICA military shooter, they wouldn't have tried to implement ideas that were there to try and distinguish itself from others in the market, like the sand system, which they focused a lot while advertising the game.
Now, I liked how Spec Ops actually integrated interactive aspects of a game into the story and how it ties into the big twist and turns the whole story around its head and finishes deconstructing the big bad ass American hero, like the moral choices (which are ultimately just there to fuck with you) but if they REALLY wanted to connect the shooting gameplay with the idea that you're actually performing the horrible act of shooting/murdering people and that you should take conscious of that and feel bad about it...they should have made the act of killing people satisfying to begin with. But shooting guys was fucking barebone, man.
Still, I'd say that both games are pretty decent in their own right. Although TPS is the last genre that should have games that end up being tolerable because of story.