Well, the time the Mexicans had to spend at the Alamo allowed Houston to raise the force needed to defeat the dictator Santa Ana. So the Alamo accomplished that.

And if your commander signifies to you through orders and through trumpet blasts that no prisoners are to be taken, wouldn't you be risking a firing squad yourself if you took prisoners? No defender survived the final onslaught. Cos was just a bitter old coot. His Generale tried to escape after the battle of San Jacinto by dressing as a private. More courage in one toenail of an Alamo defender than in that whole general. Of course Cos tried to rewrite history.