Did anyone who has been paying attention ever think it was exactly 21 million bitcoins? People just use that as an approximation.
Yeah i agree, it will be hard if we explained to someone who don't know it yet to say with the decimals, the answer will be followed by another question like "why those numbers with decimals" and we will have a long story to tell.
So i think it's okay we don't have the exact 21 mils but it's also good to know if the fact behind it is like that, maybe we need this information for future research or something useful.