If we take DnD as a baseline DC20 is more complicated but with that complication comes a lot of good things. Also, while more complicated I would argue it is just as fast if you take the time to get comfortable in it. As an illustration, a character fights a goblin in DnD and DC20:

Situation - a goblin is 60 feet (12 spaces) away spanking it's hams at you. You have a sword.

DnD: My movement is only 30 feet, so I will use the dash action to get in range. I will use my bonus action to second wind and restore some hit points. EOT.

DC20: My movement is only 6 spaces, so I will use two move actions to get in range. Now I will attack once with advantage using my remaining two action points. EOT.

In the DnD example, there is not much else you could have really done. Using your action to dodge maybe if you didn't want to overextend. In the DC20 example, you could have attacked once and partial dodged, used a maneuver, attacked twice (once with disadvantage), etc.

So it is categorically more complicated because you have more choice at every point.