As others have mentioned, there are already many units in use, so there doesn't seem to be a need for another one. Also, IMO, the more we have, the trickier it gets in conversations with people and online. I focus on BTC and am comfortable with numbers like 0.02, 0.005, 0.0003. I just count the zeros after the dot and before the number. I'm also okay with mBTC, more or less. But when someone says an amount in thousands or tens of thousands of Satoshis, I don't have an immediate idea how much that is. And that's talking about the most famous units, while there are others as well.
It does get confusing to use BTC when you're talking about a few sats, say 0.00000023 BTC, whereas 23 sats is so much simpler.
Using those two units is reasonable because their relationship is not covered in any other standard prefix like k, m, g, etc.
BTC, sats, and standard prefixes are all we need in my opinion.