They do more damage because of 3C's repeat rate, but less heat gain, the damage diffrence is tiny though. The real reason is probably that there's a variety of tech traps because of the variations:
5B > GF
2B > GF
5B > 2B > GF (Bluebeats probably)
2B > 5B > GF (Bluebeats probably)
And for each one, you can often just tap the GF to whiff it for an air tech trap, making them afraid to tech. or you can use the classic AC air tech trap. I wouldn't worry about sacrificing damage at the end of combos really, the proration has usually hit rock bottom so that you're only doing low double digit damage.