Elaborating a bit - the problem, IMO, with bags or weights is that if you camp in high winds (and we get a lot of winds where we camp in the Rocky Mountains) that canopy can get enough wind on it that you would need a LOT of weight in order to keep it on the ground.
I have thought about making some canopy weights with PVC pipe and concrete, but my fear is that if they're not heavy enough, a strong wind might catch the pop up and then my weights could become missiles and hurt somebody or do some damage.
I've seen people use water filled containers - I think the problems there are that in order to get enough weight for strong winds you need a lot of water - like 5 gallons or more per leg and the containers for those, even if empty, take up a lot of space in the vehicle. The other problem here in the arid West is that we aren't always camped at a place where I can easily get 20 gallons of water to use as a weight.
I've never had a problem with staking the tent to the ground, with the exception of a couple of times the stakes have gotten so "bound up" by the ground that I have bent the stakes pulling them out. Since they cost about $0.80 each at my local camping store I just toss them in the trash and buy more.
About the only time I wished I'd had weights was when we were camping at a spot that put our trailer either wholly or partially on a paved or concrete pad. What I try to do in those cases is ratchet-strap the pop up to the trailer, the picnic table or some other very heavy object.
