Experience gain for creature kills for players under level 100 increased. <-- Why? you can get to level 100 in 2 days currently if you plan it right by doing the epic quests, I m unsure this will help keep players in the game after they start, more likely they will just get even more frustrated when they get to level 100 and find the game gets exponentially harder...
If it is scaled in a smooth way that tapers to the current XP gain, then I doubt it will make anything worse. Kitobas' cousin would merely have made it to level 180, or 190..., in 5 hours before the same reality hit.
If, however, this is done in a way that creates a step change around 100, then I agree it is likely to create unhelpful frustration.
Perhaps a better idea (as well or instead of increasing XP from creatures below 100) would be to release reserve stamina at a number of well publicised stages, say every 50 levels up to level 200 or 250. This could be just splitting the starting reserve stam that is (still, I think) available to new players, but it might also be good just to give more of it.