I looked at the fabrics at walmart.com.
Here's my take on it, kind of an "inside scoop".
A few of the fabrics are discontinued, out of print designs. Most were released within the past half-year and are "current". Most of them do appear to be by Springs Industries.
Wholesale price on these, to any LQS, would be $2.50 / yard and then you have to add about 25 cents / yard shipping for the shop to bring it in their door.
Do the math, and you will find that Wal-Mart is making $1.48 / yard less their freight costs.
Now consider whether you think a LQS can actually stay alive on a profit of only $1.48 / yard. I think they cannot!
The advantage to Wal-Mart, selling in pre-cut pieces, is that they do not have to hire someone to measure the fabric. Pre-cuts can "sell themselves" and that is a savings in efficiency (labor).
As to the quality of the goods... yes, the cloth is thinner than, say, fabric by Michael Miller or Robert Kaufman. Personally, I would stay away from thin light-colored fabrics just because seams and threads of darker fabrics will show through them. Thin darker-colored fabrics will not have this problem.
It's really quite important that there are fabrics available at all price ranges, because we don't want anyone to have to miss out on the fun of quilting ... right?