If there was something wrong in the past and it was already found time ago then there isn't other reason to bring the olive trade back than testing well the new system. If the problems were identified, analyzed and studied the back of the system shouldn't take so so so long. They had 6 months for that, that's why people want updates
The credit based economy has 2 main problems:
1-Since game is too old and there are a lot of credits out there people tend to try to sell their crews for real money, what is against NF rules but anyways people do it. For not to mention those sales are loo$$es for SDE.
2-Game is old and the amounts of credits floating out there increased the inflaction hardly. Inmense majority of the players can't buy anything because they can't pay those prices. You can risk yourself and try to buy it for $$/olives or you just can't buy because credit prices are too high. People need more options.
Bringing back the olive system will reduce the trades of crews for real money and would bring a more "sane" economy than the credit-based economy since olive is more stable coin than the credit. Number of olives in that market would be more or less stable number because olives are spent in items sooner or later (like in this event), on the other hand credits are not all spent in ships and inflaction will keep growing without limit.
But if they preffer to keep only the credit option for trade, well ... I don't see it a great idea neither for SDE who is loosing $$ or the players, who don't have options.
A real update about how are things going on this would be nice.