I hear this question all the time and hear some exaggerated answers being thrown out. The truth is, if your catcher is lazy... it's because he's lazy. Having knee savers attached to your calves isn't going make you a lazy catcher, just like not having knee savers won't make you a hard worker.
The other reason knee savers don't make you lazy, the secondary stance. A secondary stance is the catching stance we take with runners on or with two strikes on a hitter. Whether you have knee savers on or not won't make a difference in this stance. Our secondary stance will have our thighs parallel to the ground, in a squat position with our upper body leaning forward ready to receive a pitch, block a ball in the dirt, or quickly go through our footwork to throw a runner out. This stance takes the knee savers out of the equation, catchers should not be in a primary stance with runners on or with two strikes on a hitter.
When there are less than two strikes and no one on base we can be in a primary stance; because there are no runners on and less than two strikes there is no consequence for a pass ball. Therefore we can get into a more comfortable position in our primary stance. If knee savers help a catcher feel more comfortable in a primary stance than let them use them.
If you are dealing with a catcher being lazy than you need to address his mental toughness and character. Don't blame the knee savers and neglect character issues.
Knee savers can help a catcher get more comfortable in their primary stance and help them endure a long game and a long season. Laziness behind the dish is an attitude and character issue, start there and you'll see the knee savers make no difference in laziness.