Is there any reason not to turn on Morrowind's "Always Use Best Attack" option?

In the preferences for The Elder Scrolls III: Morrowind is a toggle named "Always Use Best Attack", which defauts to "off". Is there any reason not to turn this on? Are there circumstances where I would want to use a worse attack instead of my best one?

From the Unofficial Elder Scrolls Pages Forum

I think it depends on the weapon as to whether the option should be on or off. With many weapons, all three attacks do similar damage so you might want to leave if off for a bit of variety. For weapons where there is a significant difference between the attacks, I would turn it on. I'm assuming your character is fairly skilled with their weapon of choice and therefore should have figured out that you don't thrust with an axe or slash with a spear.

However, the way the "always use best attack" option works is a little weird so I'll explain it. The iron longsword does between 1 and 18 damage for a slash. The exact amount of damage that it will do depends on your backswing (or how far you draw the string back for marksman weapons etc.). With no backswing, it does 1 damage, and with a full backswing, it does 18 damage. With most (all?) weapons, and the iron longsword is no exception, you're far better off taking a full backswing. Despite this, the "always use best attack" option assumes you're not backswinging at all and selects the attack that's best with no backswing.

The damage values for the iron longsword are:

• Chop: 2−13
• Slash: 1−18
• Thrust: 4−16

So having "always use best attack" on when you're using an iron longsword means that you will always be thrusting, despite slash being a superior attack for any sensible player. For most weapons, "always use best attack" really does select the best attack, and when it doesn't, the difference is always fairly small. Good to be aware of it though.