I'm under the impression that Inquisition was a bit of a weird middle ground for BioWare, where the game originally started as a last/cross generation title and after numerous delays/revisions finally ended up a Frostbite 3 current generation title. While I'm sure it was a challenge getting the last gen builds working, Inquisition isn't really doing much as a game that strikes me as too demanding for last generation hardware (obviously, given it's on those platforms!). On the plus side, something I love about most work done on Frostbite 3 games is that even when they're cross generation they've a number of awesome effects that scrub up nicely maxed out. Battlefield 4 still looks stunning (campaign especially), and Inquisition too is doing a ton of shit last generation couldn't, like tessellated rocks and pebbles. A mate of mine was playing it on PS3 (he only just got a PS4), and when he saw my PC build he was blown away, couldn't believe the difference.
Much like Battlefront III, a lot of what excites me about Mass Effect 4 is how it'll be made primarily for current generation hardware limits on an extremely capable and already gorgeous engine. Scene density is a big one. Inquisition has some insanely gorgeous patches of forest with dense foliage, but with fewer CPU/RAM limits how far can they take it? I also wonder if destruction will enter the picture in a big way. Frostbite is obviously attuned to destructive environments, and BioWare intended for Mass Effect (2, I think) to let biotics rip and blow stuff apart, but last generation hardware (and UE3) didn't have the chops. Now those limitations will be removed.
I'm excited to see how far they take it. Going by what's been shown so far (so very little) uncharted world exploration is back in a big way. But it's one thing to render a snowy tundra with distant mountains. What about denser stuff? Imagine seeing a rich, thick forest and being able to actually go inside it, dense with foliage, on a mysterious uncharted world. And when fighting within that forest, having explosions knock down trees.
There's a lot of potential with this series, stronger hardware, and Frostbite 3. I still think, like the Batman games, UE3 really nailed Mass Effect last generation. At least on PC, maxed out at 1080p with SGSSAA the games scrub up extremely well and look fucking gorgeous. The playspace was just always limited, with the exception of the first game where said playspace was empty as fuck anyway. I expect them to explore larger playspace with greater detail in the fourth entry.
EDIT: I mean, despite being a game that can run on X360/PS3 tier hardware, Inquisition can scrub up to look like this;