Lately I've been ranting about the Grandma Test. Simply stated, if Grandma cannot understand the technology enough to use it, (in many situations just the UX) it is objectively bad. You are losing customers to frustration. Rote memorization is the hack that got her to this point in life in her world, and constantly and consistently shifting things is breaking her hack. Key takeaway: You could have thousands of additional customers if a lightweight 2nd UI that materially does not change existed for your product.