That's a terrible idea because stuff like Sogenmu and Vergil's Spiral Swords exist. Zero's Sogenmu is already too powerful when coupled with Dark Harmonizer assist.
There are quite a few top tier characters which don't kill off of one touch and vice versa (mid tier characters who can easily kill but struggle to get the hit/get zoned out). Morrigan does not kill off one touch, Magneto usually doesn't without help, Wolverine doesn't, Nova doesn't, Vergil can't without meter/XF. In many cases even the top tiers have to at times TAC into Doom to kill a character. Low tier characters have option to do that too and it's why someone like RyanLV can make Chun Li playable because any TAC on that team is a kill. All of his characters do low damage off of a combo but one TAC equals death. Same for other players who have found success with lower level teams.
So is RyanLV playing the game "wrong" because he doesn't always kill off of one touch? What about Dual Kevin or ChrisG or Terry Bogard?
You brought up Taskmaster but he was featured in two of the previous top 8s so he isn't even that bad. Conversely, Iron Fist can easily kill off of a clean hit but no one is getting anything done with him because he has bad options. Inherently the issue with a lot of characters is a lack of tools PLUS characters like Zero/Morrigan having superior match up charts over them. Some of these heavy rushdown characters like Felicia have a super tough time against Zero because even if she makes it past the barrier of projectiles and assists, she has to contend with those multi hitting high priority normals and she loses out to those. That's why Wolverine is the most effective of the pure rushdown character, his normals are actually great up close so when he's in other characters are actually scared.
Well I did mention there being exceptions to the rules. And usually, when Ryan LV touches you with Chun he does kill either through super with Chun or infinite with morrigan.
His team is actually very very interesting. As opposed to most Phoenix teams, (let's just use mag/doom/Phoenix for example). Usually, Phoenix teams are two batteries for Phoenix. For the most part their meter builds are to benefit Phoenix and those characters will try to not use meter since Phoenix teams have a different victory condition compared to most teams (build 5 meters as opposed to just killing the other person).
Ryan LV's team is so brilliant because where as most Phoenix teams build meter to benefit Phoenix, any meter that Ryan uses not only is a huge benefit for Phoenix, but he's also powering up morrigan. In addition to building meter like a normal Phoenix team (offensive attacks), he has this super charger with morrigan assist. This super fast, very safe assist to build meter.
All complimented by Chun because her speed and mobility allow him to play some keep away and use morrigan to build almost 2-3 more meter than other traditional Phoenix teams do. It's really brilliant.
I mean he almost even uses one super battery (the assist) to benefit two characters vs, just Phoenix (for example mag/doom again that have long combos designed to build meter and do as much damage as possible without spending meter).
It's brilliant really.
And also hell yeah let's get dumb. Build meter during spiral swords etc (I do realize how silly that would be. But eff it. They all already kill off of one hit. Could benefit a character like dante who has trouble killing sometime, could theoretically build another meter during devil trigger combos and could be a nice buff to dante.)
But that's just how I see it. Lol I could be completely wrong.