The Smell the Roses one just sets the movement speed to a base number.
As Tiempko and Yula say, the XP disabler had a long and ugly, in a way, history. Basically they decided, in the end, to take the boost stone that they had and were selling in the Store at 495TP each if you didn't get one in a paid expansion, and set its multiplier to zero. XP boosts were timed consumables from Destiny points when I started. When the Store came in that September, Destiny points were deprecated. The store sold timed boosts only. The first pocket booster that I recall was made for Rise of Isengard, if I am remembering correctly and it had a cap. They put in another one with a higher cap for Riders of Rohan. The third pocket booster, which I think stacked with a premium pre-purchased back item also had a cap. When they raised the cap to 100, the cap on that item scaled up. What I don't know, but can check, is if that cap was raised with the current cap's increase to 105. Note that the XP booster never had its price cut.
All of that said, people have asked for toggle skills or a slider to let them permanently adjust their XP gain. I don't see that happening at this point, but one never fully knows what may happen in the future before it does happen.
"No sadder words of tongue or pen are the words: 'Might have been'." -- John Greenleaf Whittier
"Do or do not. There is no try." -- Yoda
On planet Earth, there is a try.
Indeed, in a world and life full of change, the only constant is human nature (A is A, after all :P).
We old vets need to keep in mind those who come after us.