Sentinal is a thorn in our sides

[Krausus]

That's besides the point, it increases your defenses without increasing enmity now. That can't be said of the new ability, therefore they are not the same. Using that similar ability in the same way we use sentinel now, may not produce the same results. In fact, I'd go so far as to say that doing so will probably backfire.

Its all speculation I'm just saying if you are taking things at face value based on description then your example is flawed

you can also look at it this way, what does Sentinel do? it reduces damage taken, what does Sentinel 1.20 do? it reduces damage taken but also increases enmity IF you perform an action after it is used for the duration. For all we know it has the same duration as current sentinel which is low.