Auto-combos don't play the whole game for you. This is the problem with Guilty Gear's Stylish Mode:
https://youtu.be/Yj4UB4oc1Ew?t=135
Guilty Gear makes actual decisions for you based on how your opponent responds to your mashing. MvCi just does one combo over and over, with no variation. At least, that's what I assume the MvCi option does. If the MvCi option is making decisions for you, then it's just as bad as Guilty Gear.
Also, wtf @ Guilty Gear Stylish Mode attacks having different frame data and properties than non-Stylish. That's double bad. You're literally playing a different character.
I think there are different ways characters can be top tier, and there are different player requirements. A character like Ryu, for example, will never require high execution. If Ryu is top tier, it's because you have to master spacing and reactions. I think a great fighting game has characters that are capable of becoming top tier through different play approaches, and one of those is the character who is top tier through execution requirements (Zato, C. Viper, Fox). The high execution isn't a justification for the tier placement, it's just one of many options and approaches to how a character can be good.
So, ideally, someone who has mid execution skill like myself would not pick C. Viper. But there would be a character that suits my strongest attribute, which is spacing, who is also top tier. Then I get to play and be happy, and so do the execution gods like MarlinPie and Sako.