I started the basic store 3 years ago. A basic store makes mathematical sense if you have more than 100 listings. I believe if you have in the 250-300 listings range it makes sense to do the more 2nd level store, which I just switched to in May. So far I've been happy. You can also put items on sale, do promotions, etc. Not sure if you can do that with no store.
Very much a benefit, especially if you do Buy-It-Now prices. 99.9% of my items are fixed price Buy It Now as I deal in mostly new items. I run them "Good Til Cancelled" which means they run until I cancel them or sell out of them, which is perfect for me because when the listing expires, if I have quantity, they automatically renew themselves. Makes less work for me.