Plethysmograph-based pulse and pulse oximetry have been around since at least the 1960s. Personally, I don't consider adding that to a watch "innovation." It's a feature, not a 2007 iPhone or a "10,000 songs in your pocket." I'm ok if you want to call that innovation, we just have different thresholds. No biggie.
Oximetry likely was a feature on Apple's Watch roadmap right from the beginning, as was pulse measurement, which came out sooner, but Apple chose to roll out the oximetry function later rather than sooner. Not a big deal. I'd be shocked if there weren't excellent reasons for doing so.
"What's the point of a fitness app, that you use GPS with, that doesn't start tracking for about 45 secs after you start. Pathetic."
When I use the Watch fitness app, it starts as soon as I touch the Start button on the screen.