For people dealing with the metric system daily, it makes more sense, if a bitcoin is x thousands an mbtc is x.
But for the ones that are not used to this, yeah probably it gets confusing just as how a race one mile 3 furlongs and 211 yards long look like ..what the hell to me..
I can see what some people see in this because it will get crazy once bitcoin is used for payments and becomes worth 30 thousand dollars or more and you will have to pay 0.0001 for a cup of tea but we aren't there yet. If people in some countries like Venezuela had to pay thousands for the same cup you can pay 0.0001. It's all the same.
As I said before it's about how easy is for some of us to deal with those prices especially since the mbtc is close to being 10x the us and the euro.
Most of my purchases are somewhere between 1mbtc to 15 mbtc.
Something costs 5 mbtc, I can simply make the math in my head and 5x9.5 , 47.5
Now, is not quite the same for 0.005 x 9500, or in case of the satoshi advocates 500000x0.000095 (hell I don't even know if I got the numbers of zeros right)
For the cup of coffee, a fancy one is something like 0.3 to 0.5 mbtc, which sounds a lot better than 0.0003 or 0.0005 in my opinion.
Of course the whole thing will not work so smooth as the price goes further up, but for now, for some of us is far easier to deal.