Your assumptions are wrong, and the reasons were different.
95% of newcomers don't buy PNC, therefore any kind of such limits wouldn't bring more purchases.
Wheel of Fortune, and Mementos to Diamonds exchange are still available, we didn't remove it.
Even the limits wasn't changed, you just can exchange once per day per a person.
The core issue we wanted to prevent was abusing WOF by 40 chars, or MemToDia with main + 11 chars looting.
We do have further plans about that, with a prevention target, but without harming regular players.
If things like this are under control, we can offer more benefits to these players, like give more diamonds.
Regarding XP, many newcomers were leveling too fast, especially with 10x and NPC boost.
One of the reasons why they were leaving the game was a debt and annoyance created, by dying on high level zones, due to lack of understanding the classes skills and game mechanics.
That's also why Johny Dalker is now in Varanas, still available but with a bit more effort, and at least after some gameplay.
5 x XP ratio is still decent, 5x more than base one, and good enough to easily level 2-3 classes, which still can be boosted with multiple potions, we may also run XP/TP events when it's lowered.