I agree with you, I too believe upgrading your chest should increase the chance of successfully blocking. It would give Turtles, and Cranes a better chance at winning duels, although I don't think it will make much of a difference in ranked.
As for increasing dashes speed, or rp regeneration, I find that a bit unnecessary. Turtles, and Cranes already struggle to defeat MA's with speed restrain, if you give those classes a speed boost it will be damn near impossible for a spiritualist to stand a chance against them on ranked. And you can get rp regeneration by simply crafting boots with it, although you can argue certain classes like DW need the rp regeneration to stand a chance against SKs. I wouldn't mind Daneos adding rp regeneration to pant upgrades as much as I would him adding movement speed to boots.