I will agree that in order for most people to be competitive, there is some cost to defray, but I think the advantage WGT enjoys is that they give the user the option to spend at their own leisure or to not spend at all for the core experience. The same core experience will cost approx $59 @ TWO.
Personally, I've put a grand total of $1 from my wallet into this game. That was last October I think and I've been riding the credit wave ever since. From my particular point of view (and I'm sure yours too), this game has been essentially free from the get go with all upgrades and balls included. I know that puts us in the minority, but my experience is the only one I'm considering if I'm thinking about reaching into my wallet. I can see the value here, there, not so much.
And it wasn't just that I was fortunate enough to win the trip either. I've also won a fair amount of real prizes like gift cards that I was able to turn things like golf clubs, a new golf bag, a GPS and a host of other new toys. Again, not the Joe Average user experience, but still my experience nonetheless. I don't foresee being able to collect like that on TWO with a $1 investment (at least for now).
I guess I'm in the camp that prefers the "pay if you want to" strategy as opposed to "pay if you want to play at all."