Don't worry about wearing a kilt without a sporran. Though it make it look a little less "kilt" like to do so, it is also a modern and casual variation on kilt wearing to just go without. I see casual pub goers who love and respect kilts but just don't like sporrans for some reason do this all the time and they still look great. As others have said, however, you will need a place to carry small items so think that part through. I have seen some men use a pouch clipped onto the side of the kilt belt as an alternative storage space.