To be honest, that's what I was told in game. I'm going to double check that and let you know if that is the case or not. If all you get from a battleground quest is experience and nothing more, then it may not be worth massing an effort. I'll try and keep you posted.
Even so, it would be awesome to mount a group to go raiding something together.
battleground update: (I got this as a response to my question on the catacombs forums.) Still, it might be fun to practice our realming together. Especially now that I've learned that my 'body' ward helps to reduce to hit chance and lasting effects of poisons, snares, and mezs.
There are 3 requirements for the quest in each of the battle grounds.
#1 you have to be in the lvl range +1(so 15-20 for bg0, 20 - 25 for bg1, 25-30 for bg2 and 30-36 for bg3)
#2 you have to take part in the capture of the Keep, in the respective battle ground.
#3 you have to cap in realm points for that battle ground.(realm points can be obtained in other places, but you must reach the cap while in the lvl range)
1 exception is that in BG3 the cap is 7125 but you only need 5100 to turn in the quest.
Reward = a set amount of experience that is enough for 1 free lvl at 19,24,29,or 35 respectivly.
So it looks as though the stats increase may have just been a rumor.