In addition to adjustable control arms, you also can use the AEV control arm drop brackets. These brackets remount your stock arms at different angles.
cheaper than control arms (US$99 vs US$300+)
addresses camber issue ("flightly" feel) caused by bigger lifts
increases anti-dive, which helps with braking performance
helps ride-quality by directing more of the force from impacts (bumps, etc) into shocks vs. the frame
leaves your front control arms mounted about an inch lower than the stock position
designed for 3.5"/4.5" lifts, not adjustable if you decide to run a lift that's bigger/smaller
There's some more detailed info over at http://jeepin.com/news/aev_brkts
Going back to your orig question, unless you're having an issue with your JK feeling "flighty" at higher-speeds, I wouldn't say that new control arms are absolutely required?