I disagree with the previous comments about making platinum harder to attain. Yes, I admit it is easier to attain Plat at IHG than the equivalent level at say a Marriott, or SPG, or Hilton brand... but it is that difference that also brings people to IHG over the competition.
For me and many of my colleagues, we chose to go out of our way to stay at IHG hotels over other chains because we can attain platinum here, whereas we wouldn't if it were made harder. If you are the few that want to stay at a hotel chain because you log a ton of stays, great there are other options for you. But for the silent majority, we choose IHG because Plat is attainable for us.