Correct, an anti-roll bar actually 'lifts' the inside wheel of your car in a turn, which reduces the amount of roll your chassis experiences.

The reason more flex makes a car easier to drive is because the front and rear of your car do not have the exact same roll centre, or the same spring rates, or dampening rates, etc. The difference between the front and rear roll rates of the car at turn in, mid corner, and on exit is constantly changing; this difference in roll is equalized through chassis flex. The rate at which these two amounts of roll are averaged out is controlled by the chassis' flex.
As the grip level of a track increases the amount of force exerted on the chassis through a corner is increased. If the chassis allows for to much flex the front and rear roll rates will be able to fluctuate too much, so the chassis needs to be stiffened for more consistent control. The opposite is also true when the grip level is decreasing.


Please see: http://users.telenet.be/elvo/9/1.html
(main page: http://users.telenet.be/elvo/ (this is a good page, pretty nice semi technical explanations of the basics of chassis dynamics))