Take a look at the cost of a sub. Then take a look at what it would cost to get everything offered in a sub on the Cartel Market. The sub is the package deal.
I see your point there, but yet there are some things that are only offered on the shop. For example that new speeder with lights. Why should I have to spend cartel coins on that when I already pay 14.99 a month? Should I not get that anyways just because I paid for my monthly sub?