PC file transfert, or internet are not the only things you can do with RS232.
There a lot of other peripherals you can connect to MSX only with RS232…
I'm talking of course about Retro-peripherals… but not all… RS232 still standard in industry.
And surely the easiest way to connect you coffee machine to your MSX… (Well… hum… it's a very old dream I had !! 
)
Around 10 years ago, I used a lot my ata-ide rs232 controller to connect to the internet with UZIX and internestor, using a pppd server on my pc-linux. Also, for file transfer, rs232 is a very goood option: quite fast compared with MSX-ethernet cards. And, the most important, rs232 its not attached to pc-drivers like nowind is. So, no matter how strange your operative system is, rs232 is allways there.
Of course, using sd/CF/ide cards is the fastest way to transfer files, but not the most confortable if you do several transfers of few files during the day (like some developers does to test their soft on real computers)
So, nowadays, releasing an RS232 controller in 2015 its not a step backwards 
What will you think about me if I say "using MSX computers in 2015 is a step backwards".
I RUUUUN AWAAAAAAY FROM HEREEEEE!! DONT KILL MEEEEEE XD
Will this card work with the fossil driver?
its kinda hard to discuss usage before knowing additional details about the card. 
I have a old sanyo rs232c, and by quickly skimming the manual of the sony card I cant really see that big difference between them..
