I can't really speak for anyone else, but, I made my original level 10 twink about 3 months after battlegrounds were first introduced. Level 60 pvp had gotten stale and I was leveling a new character. I came across some 19 twinks wanting to duel me. They were scrubs but eventually they put me in touch with a good twink who had a guild and I started doing that. About a month into twinking at 19, I came across a level 10 rogue and was having a tough time taking him down. It was all still pretty new at that point and many people thought it was hacking. I eventually figured out how to beat him with my warrior, but, it lead to me making a level 10 warrior to see if I could make something like that.
With the 19 bracket being overrun with rogues at that time, I had several level 10 warriors that were pretty amazing all the way through bc. I kept opposing premades honest and unable to simply stack rogues and healing. If they stacked heavy on melee, I broke out the tanking gear, spamstring and moonwalk the flag back. If they were heavy on clothies, I went with the dps gear intorduced them to some haste stacking and crit rating.
Through the years the warrior went from varying degrees of protection specialist or dps juggernaut, but, it was always fun.
Cata really messed things up, but, if the bracket ever got active again, I know that's where I would be. It still has pretty good balance, just not enough people