Please be specific.

Do people just not like Walmart, Target, etc.?
Have they bought a bike there and had a bad experience with it?
Do they know people who have had a bad experience?
Do they just really love their local bike shop?
Is it about the service they get?

I guess what I'm really trying to find out is...
Are there valid reasons to avoid the bikes at Walmart, Target, etc, and pay double or Triple elsewhere?
Is the stigma about these bikes justified?
For someone who just want to get to and from work each day (5 miles each way) and really isn't concerned with sports or performance, are the differences significant?