You can take SS out of the game completely and not worry about it. The rest of the T5 task system will work fine.
Not true.
SS is just the most obvious problem with it.
There are many issues with it.
Even after you did the statistical analysis, if I came up with an attribute/skill and difficulty, would you instinctively know how likely it would be to succeed without pulling out a spreadsheet? How about after a series of situational modifiers are applied? Can you do this on the fly as a player?
Most of the results also seem to be unbalanced - you are either highly likely to succeed or highly likely to fail, with only a few situations where you have a 50% chance of success. (most of the result sets you show have jumps of 40% or more of probability between the difficulty levels)
How good is an attribute? How valuable is a skill? What benefit does a knowledge represent? How does that work with the probabilities of a moving bell curve due to changing dice?
So, from a basic point of view, 1 point of skill = 1 point of attribute
In detail, the reality is something like this
+7 if no attribute is defined in Task
+3 if no skill is defined in Task
+Attribute(s) Level Listed in Task
+Skill(s) Level Listed in Task
+Applicable Knowledge(s) level (listed or not in task)
+Applicable Talent(s) modifier(s)
+Modifiers due to character action
+Modifiers due to common modifiers* see applicable pages in book
And
Number of dice rolled is determined by
Difficulty of Task
Modified by TIH rule
Modified by how hasty
Modified by JOT if skill is required
Now picture a typical new player who is trying to understand the system.
The system does not give the new player any feeling other than helplessness when trying to guess if what they are doing is likely or unlikely. There are far too many variables to balance out in ones head. Thus they don't know the risk reward ratios and so feel powerless. This is not fun.
As a referee, you can flub the numbers, house rule the systems etc., but, then you are playing your own game and not T5.
You can't even have a task where the player does not know how difficult it is in advance. So, when you do want to keep the odds hidden from the player, you can't.
Obfuscating odds when you don't want to, while making it impossible to truly hide the odds takes away options from the referee and player.
Everyone thinks about roll high vs roll low, but thats not it. It is about how easy it is to learn and use the game. It is the ratio of worrying about how things work vs using your imagination and enjoying the game.
All math/ratios should be simple, fast, intuitive. Values of skills should be obvious, as should attributes and knowledges.
The current system is complex. The current system is non-intuitive. The current system does not allow for hidden difficulty levels.
Forget the fact that SF, SS and Interesting results are by their nature, totally broken.
Find a 10 year old and explain the current system - watch their eyes glaze over. I was 10 when I started CT.
I have seen teenagers pick up and play MGT without any guidance.
Can you say the same with T5? I have yet to see a playtester pick up the rules and use them without guidance on these forums.