No Rewards for "Bonus SP"? Anyone feeling ripped off?

[Rinsui]

so essentially saying people who trust SE are delusional

What you did was not "trust", but maintaining your own interpretation of the situation.
Your "trust" was built on false assumptions; and since SE never confirmed these false
assumptions, they also didn't betray your trust, just rectify your assumptions. Don't
blame them for not being the way you imagined them to be.

and they mentioned more than once that there would be some use for them in the future

Again, no. They considered the possibility, but they never stated this as a fact.

Basically your only remaining argument is that they used wording that was prone to be
misunderstood by some readers, who chose to ignore the rest of the evidence that clearly
pointed into another direction (explicit statement that fatigue served to discourage
excessive grinding).

And actually, they gave you a "bonus" already. You had the unique and strictly limited
privilege to experience a yellow, or even a red EXP bar.

Now if that isn't something special!