WOW uses a proprietary program to create WOW. It is a huge program and everything is done directly in that one engine. Anyone they hire would have 0 experience using that program, and would probably takes weeks or months to even get a grasp of how it all works, and probably at least for the first few weeks, there would have to be someone teaching them.... and then for months and months after that, anything they produce (slowly) would have to have to have a supervisor giving a lot of feedback.
It is the reason companies like Microsoft and Google begin to fail after they get too big.. because the guys with talent and ambition end up spending all their time teaching and managing and not actually producing product. It is probably what has been happening the past year. All the guys who really know the WOW engine were not actually producing anything, but instead teaching all the new hires how to use the engine.
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Yes, they can, and will continue to nerf the EXP requirements to get to 100.. But the problem is that it is breaking the immersion of the game from 1-80. Already you really cannot level through a 1-60 zone without ending up with grey quests for the last 1/3 of a zone. While most of us certainly could care less about ´finishing´a zone, it is bad game design the way the game is set up now.
For me, I would love if they would overlap Outlands and WOTLK so that you could do either. Despite having 11 lvl 90s now, only my main has seen anything but 2-3 zones in either expansion. It would be nice to be able to use all those zones for real experience. But right now, all of my alts have done Hellfire and Nagrand, and really nothing else in BC because they hit lvl 78 so quickly and can go to Northrend where the exp is much better.