Ikelite EV Manual Controller

Does it REALLY make THAT much of a difference vs. just using the limited manual settings that are built right into the strobe?

I know there are a lot of pros on here, who have every piece of gear imaginable, more lenses than I've owned my entire life, etc. who are going to say, "YES! Full manual control for your strobes is necessary."

But to keep things simple, couldn't you just use the few manual settings on the strobes themselves, while bracketing, and come up with the same results...or if not, damn close?

You could, certainly. The main benefit of more manual settings (or using TTL) is that you have more flexibility with the aperture at which you shoot. Aperture determines depth of field so with more manual settings for the strobe you have more options for DOF.

it is probably more aimed at the DS-50: that had only F / TTL and off. The current strobes have around 6-10 power settings on the strobe (or use the controller on the housing.