Many developers updated their games to run perfectly on the iPhone 6 within weeks after Apple's latest phones came out last September. But not Sega.
That said, is anyone that desperate to play 20-year-old games on your brand new phone? Either way, it's beyond the point.
Why has it taken this long, then? It's anyone's guess. Perhaps it has something to do with the company being restructured and the San Francisco office being shut down.
In any case, at least you can play the speedy platformers on your iPhone 6 and 6+ now.