Well I understand there can be reason to toggle the xp gain off, I'm not against.
However, the fact that every mmo I've played do these double xp bonuses in events and festivals (very welcomed by the community), the items that make players get more xp are very popular, the custom (pirate) servers of many of these mmos are well know for double or even 10x the xp, etc.
Imo it seems that the majority (not everyone) want to gain more xp and not less. So implement resources on this maybe is not a good idea.
By other way, I dont believe the "Turbine conspiration theory", like they want us reaching the level cap asap to make us spend tps tuning our LI's or making us to start new chars to spend tps with. They want us playing the game and buying questpacks, expansions, etc. and that won't work with a parked player.
Keep doing double xp bonuses but don't make them common.