WoW itself wasn't even as innovative as the fanbase would have you believe. Blizzard did engineer the lore and story using their Warcraft franchise to create a setting but the UI and features in the game were taken from numerous other MMOs that came before it.

Incorporating ideas from other games isn't inherently bad as long as the developer tries to also innovate some of their own ideas or improve on what was done before. Sometimes they fall on their face doing so. Take FFXIV's housing issue. The system was originally created around being an FC feature and for the most part it seemed to work great. Then it was changed to support individual players and this is where they have kind of fell flat and are now in a situation without a real solution that isn't going to amount to more than a Band-Aid and any proper solution is going to upset someone somewhere.