[falcolas]

None of the people who really drove the creation of WoW back in the day exist at Blizzard anymore. They don’t play WoW, they don’t even play computer games primarily (at least, that’s what they say).

There’s nobody to really lead the charge to create “old school” content for WoW.

[vanterdon]

Plenty of them are still at Blizzard, though OSRS did a good enough job of having new staff and still sticking to the original game's design philosophy. It's really not an issue, it's easy to see the bounds of how the game could expand within the original design philosophy.

For example, no LFG, keep the level cap, no transmog, no multi-server sharding, no removing RPG elements like hunter ammo, things of that sort.