Why haven’t sextech companies done research on how different vibration frequencies might improve or lessen the sensitivity of mechanoreceptors?

Recently I ordered some original (discontinued) Lelo Ina vibrators they found for me in a warehouse. When they arrived, they were not the same as my old ones. The clitoral arm was stiffer. It changed the quality of the vibration, making it numbing rather than pleasurable. The effect is enough to make me question their safety and whether such devices should be FDA regulated.