"screwing the high leveled players", infinte loop?

There's enough content for pre-third jobbers. <_<
Why do they need more?

Because the best way to make money is by making the initial grind easier and more fun. People get hooked on a polished game and decide to buy NX.

People who are already high leveled are basically hooked and Nexon feels they don't have to do a whole lot to keep those people playing. They "demand" new content but a lot still continue to play (and pay).

It's such a smaller part of the player base, from a business PoV they would rather focus their efforts on 1-70 gameplay to entice more people into playing (now take away the L).