Ok, assuming it works like 3.5:
if you have 18 cha + 8 in the rest for a sorceror, you start with 3 hp, AC 9 and fort, ref -1 and will +1
If you have 16 cha, 10 wis, 10 con, 10 dex, 8 int, 8 str, you have +1 AC, +1hp, +1to all saves. So if you face each other, you are better off with lower charisma. your effective hp is higher. A magic missile has a lower chance to kill you. Spells which do more damage, but allow a save have exactly the same chance to go through your defenses. Your most efficient weapons are rays, which target AC. You have a higher chance to hit and the enemies hp are lower!
If you face monsters at higher level, and you don´t win initiative, 5-10 more hp and better AC saves your life.
I don´t know which game you play (scry tele kill?) but in D&D I play, high main stat is not needed.
And rogues in 3.5 should maximize int before dex.