well, its logical one would choose TURBO so why there has to be a NORMAL option?

it would only endanger the player if he accidentally chose it?

???

i don't know

Although Normal runs slower...it is more accurate.
Because it runs slower,people think it's LAG...this is a misconception.

Normal is actualy more accurate than Turbo, because it runs slower, it allows you to track your opponents better.
Hence it makes all those Ryu players that rely on jumping left to right firaballing (lag shielding/lag-teleporting) non-stop EASY to flatten.
It also helps "inhibit" optic blast athons by n.o.o.b.s. and the unskilled. (at least from what I've seen and experienced.)

i always win in normal mods but about half the time i dont win in turbo... ;)