At first, I'll admit, the ads were jarring. I didn't like them (and still don't). +1 on removing them for members.
But, after reflection, I'm okay with them. Most websites that I frequent have ads, and most are far more annoying and obtrusive than BPLs. I still go to those websites because of the quality of their work, and I accept the ads as a minor compromise for the sake of a larger goal.
I'm old enough now that I can no longer demand ideological purity from myself or others. We are entrapped by the larger structures of our world, and we escape what we can when we can (thus, backpacking). But the world is still there, wilderness is still disappearing, and our world climate is changing--no amount of trip reports will solve that.
However, we are still capable of change (hopefully, for the better), and BPL has been a source for me as I re-discover and re-search for simplicity and beauty. If it takes some mildly bothersome ads to keep that alive, I'll accept that compromise for the sake of the larger prize.