HIRO kun: I didn't use the BACORTU spell at all, so I didn't know that difference existed. lol.
You may not use that particular spell (though I find it useful (in versions where it works) against enemies that use spells that CORTU can't block), but enemies do, and by playing a version where that spell doesn't work, the strategy of having to counter it doesn't exist.
Example: Some enemies can cast the PALIOS spell, which dispells CORTU and BACORTU. If the enemy has that spell and other spells, CORTU might not be the best protection, as the enemy can just dispel it. On the other hand, if you cast BACORTU and the enemy tries to use PALIOS, there's a chance of that spell fizzling. Also good for preventing enemies from using CORTU and BACORTU themselves.
By the way, SNES Wizardry 5 is the first time I found a way to cure LOST in a Wizardry game. (It's also possible to cure it in Wizardry 2, as well. Unfortunately, I'm pretty sure you can't cure it in the Apple 2 version of Wizardry 1, though you can at least prevent it with a glitch that can change a character's condition from ASHES (or STONE, or (in theory, but this glitch doesn't work during battle) SLEEP to the unused AFRAID condition. Just heal and fight a battle.)
Speaking of which, isn't it interesting how the Wizardry 5 developers took a condition that was in the earlier games but unused (AFRAID) and actually gave it an intentional function and some ways it could actually be inflicted?