Well you may be right. However the "big guys", also have to be able to deliver. If they can't provide a top product for top dollars (yes it will cost), then the smaller ones with a strong user base may be able to compete. Provided they are producing a reasonably reliable product.
In the years and a half I've been using avast, I've seen the improvement. There's still room for more. The users here can help alot with submisions, avast on the other hand has got to be a bit faster on adding submitted files. Being first out of the gate can go along ways in attracting new customers.