Will not argue with decisions you guys make. But I doubt the reasoning given here stands. Percentages won´t change wheather I want a pokemon or not. If the percentages vary from area to area, they might change where I hunt but not that I hunt. Instead, they give me an approximate time frame I can calculate with, which, at least for me, counters the disappointment when I "wasted" two hours of hunting a special pokemon (I look at your, Murkrow route 7).
Then again, even if you don´t give a reason for that decision, I am fine with how it is. I just don´t think it would take the point away.