Or....., and this would be more my take on it, the old numbers were very very underwhelming and the new numbers (if accurate in the field) are making a step toward more contemporary standards.
Yup that's my take on it. Time is long overdue to modernise a little and gain some efficiency (losing some weight and adding more water-cooling would be good too)
Put it this way, around
1983 when BMW decided they couldn't just keep pushing out the old air cooled boxers they were criticised when their new K100RS with it's 1000cc (8v watercooled 4) motor was only pushing out 90bhp when the Japs had long since cracked 100bhp/litre - conservatism at the factory seemed to be the main reason. The later 16v version upped power to 100bhp, they still could have gone farther.
When they launched the 1100cc oil/air cooled boxers in 1993 they also pushed out 90bhp, the 1200 motor was up around 110bhp and the later dohc motor was about the same but a bit torquier. When they adopted watercooling a couple of years ago then then pushed power to 125bhp.
So if HD can pick up some engine efficiency with the new motors, and hopefully ditch some weight with the new chassis that is allegedly on the way for 2018 then we're looking at bikes that should perform significantly better than their predecessors without just trying to grow the motor.