I think I now know why. There was a TED talk by Simon Sinek regarding how Apple sells its products to its customers by making you believe why you should need one than without one.

http://www.ted.com/talks/simon_sinek_how_great_leaders_inspi...

The keynote didn't really sell me the watch. To me it was more like a 'me too' smartwatch but with several customizable options to set it apart from the competition. They should've stick with one model and iterate later like they always did.

But I agree, if the presentation was worded like this, I probably would've bought one in a whim and wouldn't think the heartbeat thing as gimmicky.