Is there a reason to ignore the decree to pound the pillars?

Question

Is there anything I miss if I don't "pound the pillars" in the basement of the castle? Am I making any of the stars inaccessible by doing so?

Answer 1

Yes, you'll miss something if you don't pound them; no, it has no negative effects.

Pounding the pillars drains the moat around the castle, allowing you access to the Vanish Cap level. That level has one star, from the 8 red coins.

Answer 2

You can safely pound the pillars, you will gain access to new stars. And as a matter of fact, no star is missable, you can still pound the pillars later.