I agree/disagree.

The way the system works for rested XP to be useful at higher levels and not completely overpowered at lower levels it needs to work off of a percentage as opposed to a flat bonus. But you are right, that it is a lot more effecient to use your rested XP on a higher level character rather than a lower level one. And to make matters worse, if you're trying to speed level one class, it makes you have have to work on that specific class when you log in each time before doing anything else in order to take advantage of your rested XP.

My suggestion would be to just let us "pause" or "enable" our rested XP, so that we can apply it to the class we would like it to, but keep the structure of the system of how it accumulates entirely the same.