As bitcoin have got a legal acceptance getting used similar to the conventional currency, there is no need of such a new token targeting the Tokyo games. This will surely decrease the usage of bitcoin when the token comes out for usage, because it's been developed by the government and the government will surely insist to go with J-coin. Maybe the legalization might be an initiation for people to understand about the digital currencies.
sure, there's no actual need for it, as is the same with most other things in this world. however, the main point here is that there's no real reason not to have it. besides, there arent many downsides that this little experiment could have, aside from some bad pr if the project were to bomb. when the coin is released to the public, actual exposure to cryptocurrency would increase dramatically, and people might feel more comfortable with the idea of using cryptocurrency if they don't already by using one created and backed by the government. one though that comes to mind is that the japanese government might be using this was a means to move japan forward with use of digital currency (and i don't specifically just mean cryptocurrencies, but also credit cards and the like in general usage) as paper cash is still used more often than not; a lot of restaurants and merchants don't even have card readers to be used form personal experience, and only accept cash as the means of payment.