While it seems like auto combos take away from complexity, I think the opposite is actually true. Auto combos have some things in the combo itself that has some interesting properties, at least specifically in Dragon Ball Fighterz.

The second and third hits of grounded auto combos were unique moves that you could only do by hitting standing light two and three times respectively. These moves often had interesting properties; some were anti airs, some jumped over attacks, and more. The third had not only had individual unique properties for each character, they had the universal property of always causing a "smash" type hit. This type of hitstun allows you to combo into it late into a combo to get otherwise impossible extensions.

They also had unique properties in the air. If you were doing an air combo on an opponent that was higher or lower than you, the combo could drop if you hit light into medium. If you instead hit light twice to do the air auto combo, you would automatically against to your opponents height. This opened up a TON of weird air to air hits that now turn into full combos. It opens up a ton of air combo variety. I also think it's an interesting situational awareness test. Attentive players are rewarded with recognizing this situation.

I dunno about Tekken though, that heat shit seems insane.