I'm going to go against the trend a bit here
Love the gadgets myself, the more the better :-) One of the main motivators for me is looking at the stats after a ride, how far, how fast, what was my heart rate on that segment/hill etc, its fun and enjoyable. Obviously each to their own but it seems some people dont understand that other people get enjoyment from these devices, and the figures they give you. To say forget about the Garmin and just enjoy the ride/scenery, to people like me, and it sounds like the OP as well, would just take half the enjoyment of cycling away.
However, while its good to take note of the numbers, all you are looking for are trends. I wouldn't say I take too much notice of the actual figures, but if it shows my speed increasing on a particular segment, or recovery time for a ride that use to be 12 hours is now say 8 hours for example then its good to see that my fitness is going generally in the right direction.
As the Op says, there are a lot of science behind these metrics the gadgets produce, most of the numbers are not just picked from thin air and can be a useful motivator.
The one caveat I would add is wrist based heart rate monitors for cycling (your fitbits etc) - see DC Rainmakers review of any wearables and the figures they produce for heart rate, while cycling, are hugely out compared with chest straps . Even allowing for my 'ignore the actual figures just follow the trend' above is useless as they tend to produce such wild erratic figures that they are, in DC's words (
just for cycling, and its just wrist based wearables) "useless". For the general 24/7 measuring heart rate etc they are fine, but any high intensity activity sends them haywire, in his opinion.
Continue to enjoy the rides, continue playing with your new toys, and enjoy them both :-)