Don't play dumb, you know that Dragon Age (after Origins) and Mass Effect are not considered party based RPGs.
Yet those games are almost entirely about interacting with your party between missions. When Larian says your party is important, there's a good chance they mean it's important in the BioWare sense, meaning you talk to your companions A LOT, not necessarily that controlling them is important to combat.
When a developer says, "missing based on dice rolls sucks in a video game," they're making an action game. Because missing based on dice rolls is a normal mechanic in turn based or RTwP combat, as everyone at Larian knows. Dice roll based THC only sucks when you have third or first person action combat, like in Morrowind.
And the math is pretty brutal. Larian's been working on this for over two years. They said they had 200 people on it before, now they have 300 people on it. How much does the average game dev cost per year in Belgium, Ireland or North America? Say $50,000? That's $15 million a year with the current size of the production, just for labor costs.
It's really hard for me to conceive of them spending $30 million or more on labor and then limiting the size of their target audience by going with non-action gameplay.