HTC is really getting mileage out of the One’s industrial design. The original, the Mini and — now — the Max.
Although I’m sure keeping a similar look keeps costs down, a fingerprint sensor doesn’t really ‘fit’ into the One chassis. By chance, Apple already had a convenient (and prominent) space for the fingerprint sensor to go in the form of the Home Button. HTC has no such luck applying the same strategy as the One’s design has very little free space on the front of the device.
As a result, HTC has resorted to shoving it on the back of the phone which is very much inferior, not least because the sensor itself is not visible in normal use. Out of sight, out of mind.