people are turned off by having to feed rodents and live insects, so that's why chain stores often try to make it seem as though they can live without it. In my opinion, that is a really crappy diet and probably the reason that the inexpensive savs die so often in captivity, because most people that get them don't understand the kind of care they need and end up keeping them in an aquarium on sand or carpet with low temps feeding them crap like that.
Same thing goes for other lizards. I've walked into chain petstores a few times to find bowls full of those nasty looking canned crickets and meal worms in the lizard enclosures, and pelleted diets as well. Pelleted diets made by repcal I don't have a problem with. I have a very picky bearded dragon and even though he will rarely ever touch a good salad, he loves those. But, if I can get him off those and onto a good diet based around 60-80% fresh greens and veggies, and the remaining being insects, I would happily toss the pellets aside. I admit that it is my fault he is like that though because I spoiled him with crickets, and that's the wrong thing to do.
Most people going into petco or petsmart to find a "cool lizard" aren't going to care much for providing for their specialized diets, so they think that buying canned and pelleted foods will help them...what it really does is harm the lizard. This is obviously very generalized, because I'm sure their are lizards out there that can be successfully maintained on just premade foods, but that's really not the way to go. I remember a while back seeing that one company (was it T-rex?) had actually made sausages that you could feed to snakes to replace feeding rodents. That just seems stupid to me.
On a side note, my mom was in a local petshop a week or two ago, and she always finds it so terrifying to see parents there buying reptiles for their young children (I find it terrifying too, since none of the parents know what they're doing). Anyways, she was at the petshop, and this mother was getting two young leopard geckos for her young children, and the children had already taken the supplies up to the front when the petstore employees finally hinted that leos need to eat crickets and mealworms. I don't think she liked that very much.
A long rant, but I just think it's stupid to get a pet and then not give it the best food you can, especially when the pet is not domesticated, because their natural instincts will tell them that what they're eating isn't what they should be eating.