Continuing the discussion from Release 172: Alts and World Levels!:
“Rebalanced slingbows
–Added multishot variants.
–Removed cooldown to make repeaters better.
–Changed gravity effects for different types.
–Balanced damage, and speeds etc.
–Tweaked names.
Removed gravity from grapples.”
feature for now… but the devs are always tinkering and re-evaluating things like this so i would expect this to change at some point… also with the up coming forge… there may be a mod for available to fix this issue… (with some sort of trade off im sure 
)