I don't check bags either, but I've heard from a decent number of frequent travelers, particularly women, that products they use can't be repackaged (e.g., aerosols) and are either too hard to find at various destinations or that the expense and time of purchasing them at destination on each trip would be burdensome. And your argument could be extended to say that, should TSA ban clothes in carry-on, it wouldn't be that hard to just repurchase all of your clothes at destination each time you travel.

I don't believe airlines should be allowed to exploit TSA rules to force passengers into paying a new revenue stream. If the airlines would publicly call for TSA to abolish the war-on-water, when the change would immediately cause a decrease in checked-baggage numbers and weight, then I might give them some credibility. But they don't. Instead they're just grabbing for money hoping to lure pax with "low" fares and then trap them at the airport with fees.