One way to look at percentages is as a quota. "20% of our speakers this year shall be women!" Right or wrong, a lot of people don't like this.
Another way is to use percentages as an indicator of how well your outreach is going. If you have, say, 5% women/minority/whatever speaking in the first year of your conference, that metric could act as a swift kick up the butt that you're not doing enough outreach, your CFP is poor, you're not promoting the CFP in a diverse way, etc. You work and improve, and then in year two you might notice you ended up at, say, 30%. Hurrah!
Both approaches involve percentages and measurements, yet the second is not an attempt at fulfilling a "quota" (even if there's a target % to reach) and should be more palatable to everyone while still ensuring efforts are made to increase diversity.
Another way is to use percentages as an indicator of how well your outreach is going. If you have, say, 5% women/minority/whatever speaking in the first year of your conference, that metric could act as a swift kick up the butt that you're not doing enough outreach, your CFP is poor, you're not promoting the CFP in a diverse way, etc. You work and improve, and then in year two you might notice you ended up at, say, 30%. Hurrah!
Both approaches involve percentages and measurements, yet the second is not an attempt at fulfilling a "quota" (even if there's a target % to reach) and should be more palatable to everyone while still ensuring efforts are made to increase diversity.