Picked up Slicing at lvl 21, when I had about 14k credits.
Level 34 now, and have 350k, great gear, and extra goodies bought. People with out slicing aren't necessarily screwed, but they will be far behind in cash.
Except if you spend a night farming you get hundreds of thousans of credits from looting ... no slicing necessary. What slicing has going for it is that it's comfortable steady stream of credits. But you sacrifice self sufficiency in your crafting profession for it.