Previously in the game you had to rebuy your ship and all equipment every time you died. This introduced a balance where you had to choose the right loadout for the right situation, and your play style, rather than just picking all possible equipment. It also introduced a gameplay element where if you did pick an expensive ship, you would be more careful with it, which adds an element of risk.
This would have worked, and would have been fun, if only experts played the game.
In reality:
1. There is only a minor difference in effectiveness (say 10%) between the most expensive and the least expensive ship.
2. There is a wide variation in player skill.
So what happened is some newbie would pick the most expensive ship, and since the ship itself only accounted for 10% additional effectiveness at best, he would just die repeatedly the same way he would have in the least expensive ship.
In the end, the good players had virtually unlimited money from killing newbies. The newbies were always stuck with the worst ships. To the good players, the credit system did nothing, since you could always buy whatever you wanted anyway. To the bad players, the credit system was a negative, since you couldn’t use the interesting equipment.
We’re changing it to be more like a traditional system. Items cost a lot, but once you buy them they are yours forever. The only part of the former system we are retaining is you still have to buy ammo. the ammo for the very good items will be tremendously expensive, and the carriers will be tremendously expensive.