I also don't use the term "White British" to describe myself even though it is the demographic I select on surveys. These terms are useful for demographic meas

I also don't use the term "White British" to describe myself even though it is the demographic I select on surveys. These terms are useful for demographic measurement, not for personal description. Another commenter gives a good explanation – that the + is there to include those who identify as mixed race. Latinx is used to aggregate Latino/Latina identities. These terms are useful with even the smallest amount of interest given to why they might be. I'd encourage you to be more curious rather than jumping to the conclusion that this stems from some cultural over-sensitivity.