There's a good, quick and easy fix to this. Simply remove the need for Fields of Valor to require monster that give EXP. Since you can only use it once per gameday, would it really hurt so much to give lower level players a quick 300~800 exp extra every hour targeting something they can take out more easily?
It'll make Fields of Valor popular again, and in turn also make low level players happier with some extra exp.
Maybe I'm missing something but I fail to see how that helps at all. You might complete the page faster but then that's the only exp you're getting for an hour. I'd rather take 30 minutes to fight 10 mobs that give ~80 xp and get the bonus than finish off 10 too weaks in 10 minutes and get a lesser amount of bonus exp from doing a lower level page (where the mobs would be too weak).
For example, let's say you're level 25. You could do Valkurm Dunes page 4 against 4 Damselflies and 4 Brutal Sheep, with levels 20-23. Base exp per mob would be 65 (level 20) to 80 (level 23). So your average exp per mob (assuming even level distribution) would be 72.5, and you're fighting 8 enemies of this sort, so in completing the page you'd get 580 xp (8*72.5). Upon completion, you'd earn 550 bonus exp. Again, in my experience this should take about 30 minutes, so 1130 xp in 30 minutes. Nothing fantastic. If you continue fighting mobs for the next 30 minutes you could get another ~580 xp, for 1710/hr. Again, nothing fantastic. If you're smart, you'd start the page right before the end of the day, then you could do 3 in a row, 1130 per page * 3 pages = 3390 xp in 90 minutes, or 2260/hr. Slightly more respectable. And this is without an exp ring, which you might as well be using since you can't really apply them to high level jobs now thanks to Abyssea.
Now let's say you do a page where you aren't required to earn exp from monsters. For this example, still level 25, we'll use La Theine Plateau page 4, 5 Mad Sheep 3 crabs, 420 bonus exp. Aaaaand that's all you got, because the enemies don't give exp. Sure, it might only take you ~10 minutes to finish off the 8 mobs you need, but the 420 xp is all you got, and now it's ~50 minutes until you're earning exp again.
The idea might be useful if you're farming to earn some extra xp, or just looking for a quick boost between doing other things, but if you're just looking to earn exp you'll get more by sticking with the current design.