The article cites the fact that the coupe is sold for just under $25,000 with a manual gearbox and no options added. The manufacturer fears that the cost of making it a convertible would make the drop-top too expensive to attract a large enough quantity of buyers.
It will however be sold to other markets around the world as a Toyota wearing either 86 or GT-86 badges depending on the market. There is no word as of yet on whether there will be a Subaru BRZ convertible.
[Source: Automotive News]