They probably want to make sure that BGs don't turn into a situation where every BG you play has fully geared PvP toons - which makes it easy to hate on new players who aren't geared.

Probably at least 1/2 of my BG fun is killing under geared people. It's awesome to see them get one shot, or see 60k crits. It's also a nice break when you go against a poorly geared team.