I don't really understand the reasoning behind depleting it faster once you are below 50% either. I suppose it's to combat bots somehow. I was like you, I didn't really pay any attention to my capture rate. But after they announced this change, I looked and saw I was hovering around 25%. Hmm

So I decided to stop playing for awhile and just rent out everything. The idea of missing legendary pulls is eating at me, but even accounting for the legendaries I have pulled in the past my average take is much higher now, so it's a win I guess. (But I miss playing now. haha)