Is it necessary to attach sofa legs?

I just purchased a new sofa. It came with legs, but they need to be screwed in with a screwdriver through the fabric and then the wood part underneath the fabric at the bottom of the sofa. There's no pre made holes, so you just have to screw the provided screws until you create a thread in the wood. I think it would be quite easy to screw them on unevenly and end up with a rocking couch. Does it make a difference to the comfort/durability of the sofa if I decide not to attach the legs? It seems to be fine without them.