The biggest difference is you capture and hold nodes in Seal Rock. It's not enough to just capture it, you've got to defend it (which I admit was arguably the most fun part). This promoted active combat, from both sides. Either you're fighting to cap it first, or you're fighting to keep it. Either way, you were fighting, and I understand the frustrations with Shatter seeming a bit more passive in that regard.
Still, you can't play Shatter like Seize, and vice versa. Nor should you. But objectives to win are, and always will be priority over kills.
