I think this would have been a Mace we all could have lived with.

Master of the Jedi Order
Mace Windu COST 90

REPUBLIC

HP [150]
ATT [+16]
DEF [22]
DAM [20]

Special Abilities:
Unique. Melee Attack; Triple Attack
Lightsaber Duelist (+4 Defense when attacked by an adjacent character with a Force rating)
Vaapad-Style Fighting (Scores a critical hit on an attack roll of a natural 18, 19, or 20)

Force Powers:
Force 2. Force Renewal 1; Master of the Force 2
Force Crush 4 (Force 4, replaces attacks: range 12; 40 damage to 1 target enemy. Huge or smaller characters are considered activated this round; save11)
Lightsaber Assault (Force 1, replaces attacks: Make 2 attacks)
Lightsaber Defense (Force 1: When hit by an attack, this character takes no damage on a save of 11)
Master Speed (Force 1: This character can move 6 extra squares on his turn as part of his move)
Shatterpoint 2 (Force 2, replaces turn: range 6; choose one target enemy. For the rest of the skirmish, this characters first attack each round against that enemy is a natural 20 and cannot be prevented or redirected.)

Commander Effect:
Allied characters first attack each round on a Shatterpointed enemy within 6 squares is a natural 20.

Not at a cost of 90. Also, I'd never want to see another high-cost Mace with Triple Attack and no Intuition, Suprise Move or GMA. Too many lower costed pieces in this game can move 6 and do 120-ish damage.

I get what you are trying to do with Shatterpoint, but Shatterpoint itself was such an epic fail to begin with, it's hard to work around it. With all the other options on your Mace, you're going to be hard-pressed to justify a use for your Shatterpoint 2. At a cost of 90 and replacing a turn, you're going to be low on activaitons to begin with and giving up one like that would be difficult.

This is a Mace that I think is a good start from one of my old custom sets:

Mace Windu, Vaapad Master 70 points R
Republic
HP: 150
Def: 21
Atk: 15
Dam: 20

Special Abilities
Unique; Melee Attack; Triple Attack; Greater Mobile Attack; Lightsaber Duelist;
Vaapad Syle Mastery (Scores a critical hit on a natural roll of 18, 19 or 20. Critical hits by this character cannot be prevented or redirected and the damage cannot be reduced.)

Force Powers
Force 6
Force Absorb
Lightsaber Precision
Master of the Force 2
Master Speed
Shatterpoint

Of those to master Vaapad, only Mace Windu was not mastered by it.

He's all offense, to signify his combat style in full Vaapad mode, but you might go for the Shatterpoint to set up a big next round even if your target moves away.

I originally designed this Mace with Double and Twin Attack. But I figured that might make him a little too undercosted at 90 points, by being able to move 12 and Quad attack at +16 attack with Vaapad. This Mace has Assault along with Renewal which basicly is a Greater Moblie Double Attack. Yes there are lower costed pieces that can dish out more damage, however they do not posses the 22 base Defence nor the 150 hitpoints. They also do not have access to the 40 auto damage this Mace has.

Your right on Shatterpoint being useless, I'd say 95% of the time. Shatterpoint 2 on the other hand by itself and the synergy with his CE would see a whole lot more use than 5%. On a guess I would think that it would see useful play anywhere between 40-60% of games played with him. It all depends on squad design and character strategy though.

With regards to your design. He plays like a high risk high reward piece with no defensive abilities. IMO I would have to say that Shatterpoint doesn't even have a 5% usefulness on your piece, since your Mace can move from 12 away and Triple Attack. Might as well get rid of it. But he seems costed about right other then that, since he has no Force Renewal nor defensive abilities (not counting absorb).