Exactly. People are used to doing it that way, and it fits in nicely with programs/systems designed to handle currency.
I do not think you understand a thread
How come it fits nicely with programs/systems designed to handle currency??
Because they are designed to handle decimal currencies (with 100 subunits). It would be stupid not to follow an already established way of doing things.
For those who don't get the significance, this is important for legacy software which often has restricted input size. For example we use "bits" (uBTC) internally for financial accounting. All Bitcoin ledgers are in uBTC. Quickbooks (and lots of other software) assumes that exchange rates will fall into a specific range and thus only has so many significant digits).
1 uBTC = 0.00045 USD
1 USD = 2222.22 BTC
Using satoshi wasn't (haven't rechecked lately) possible because the exchange rate fields didn't have sufficient digits
1 sat = 0.0000045 USD
1 USD = 222222.2222
This was even more of a problem previously when the exchange rate was lower. Even if sat:USD exchange rate fits currently in your accounting software be sure to check what a 75% (or 90%) exchange rate drop would do. It would be a nightmare to have an accounting system in place which simply fails if the exchange rate drops below $XXX USD per BTC.
Perhaps we can use "satoshis" and quote prices (or do accounting) in "millions of satoshis" or "thousands of satoshis." We can use Msats or ksats for writing, but in spoken language people will say 2.5 million satoshis, or 35 thousand satoshis. They won't say "megasats" or "kilosats." For example, someone on CNBC would say "Bitcoin is currently trading at $4.51 per million satoshis." This has the added benefit of promoting public education about the resolution of our currency.
I think the problem with the milli- and micro- prefixes are not the fact that they are SI prefixes, but the fact that division is harder than multiplication. If someone says 100 uBTC, I immediately say "hmm, there's 1,000,000 uBTC in a BTC and he wants 100 of those, so he wants 1 / 10,000 of a bitcoin" and my brain sort of hurts. But if someone says 2 million satoshis, then my brain doesn't seem to do any math. I just "get it."
I think most peoples brains work like this (multiplication by powers of 10 is obvious but division requires thought).
So again, I prefer bitcoins and satoshis.