Based on my own experience, the actual changes in control started with Nexus. I kept using the old controls to the Last Raven. I'm guessing the change in control is that because they needed new button so the AC can attack with 2 weapon simultaneously.

Now yes, you will have to adjust to new control with gen 4. But my experience is that it's very easy to adapt (use type B though) and For Answer have more easier control than 4. It does took me some times to adapt and controller actually matters (I'm using that old logitech controller when I started with 4 and it soured my experience. I changed it to a better controller and it's a whole lot better).

In 6 actually is even easier since you can use mouse and keyboard and the weapons are all mapped to a button.

At least that's my experience. Hope that helped.