Q. Why are these plugins available at cost and not included by default?
A. This is because of following reasons:
Everyone wants a low startup costs.
Not everyone needs them.
Thus the default functionalities are available to each store and store owners who would want more features can add them as they grow (not necessarily buy them all at one go) thereby phase out investments. Not everyone is willing to spend US $3500-4500 for a Custom ecommerce solution but many are ready to go for a Sub US $1000 ecommerce proposal.
