Even though that is a noble reason on the first look, I still find it sad and not desirable in most cases. If someone is worried for these reasons to tell the truth, it can make a huge difference on the wording. How you are being honest to someone can significantly impact their reception and thus their feelings in this regard.

An example: "I didn't remember your name, because I don't care enough about you." Versus: "I'm very sorry, it seems I have forgotten your name. What was it again?"

Besides, not remembering names of everyone is something a lot of people can relate to. If you are honest in a friendly manner an invite others to understand you, you may find that most people don't have bigger issues with accepting it. And even if they are not perfectly happy about it, they are usually able to take it.

In cases like remembering names, I think people tend to be dishonest more often because they feel they will be judged for it rather than for them trying to be considerate.

Also, depending on the person, being honest is the most considerate thing you can do for someone. From my experience, there are not many people who prefer liars. (<- This sounds harder, than I mean it.)