Using Game time cards to purchase transfers/booster packs
I'm not necessarily against this, but a few things come to mind -
First, the booster packs tend to be $9.99. Game time cards tend to be $15 or $30. Now, the second works out mostly fine, as it would let you buy three packs. But what happens to the leftover $5? It's generally ok if you want a jetpack, I suppose, but somewhere there's going to be that "leftover five bucks," and I'm not sure NCSoft would want to be responsible for being, in essence, a savings account - or that a policy that says "These are converted to points, no refunds" would go over well, though I think the second would be needed in this case.
It's a bit more appealing to use them as "points" to purchase (using your terminology) if I play multiple PlayNC games (and the developers, including non-NCsoft developers, such as Arenanet, agree to use those points.)
Second, as far as not being able to use credit cards, you can purchase using Paypal as well, which links to your bank account. There are also prepaid cards that can be used.
May have been suggested before, but i do believe that NCsoft should consider making it possible to pay for ingame things like the booster packs etc. with time cards. Just like the game cards can be used to boost funds on Exteel or whatever, have it that you could delegate a card to add so many points to your account which you could then use to buy things like the booster packs or the ingame items.
There are still many of us out there who can't use credit cards and still would be quite happy to spend an extra few dollars on some of the booster packs etc.