I like compression straps on a pack so I can keep the load close to my back (and not have to lean so far forward to balance the pack's weight).
Without compression straps, things can tend to collect in a clump at the bottom of the pack, instead of being high and close to my back. Depending on your gear, you can dance with that by using some tricks - on low volume trips or after you've consumed much of your food, you don't pack your puffy layer or sleeping bag/quilt so tightly but leave it fluffed up in the bottom of the pack. Then you load dense items high and/or between bag and the back of the pack so it is wedged in close to your back. Note that you are also trying to keep the smooth, cushioned things against your back, so it takes some practice to get it all dialed in.