You're missing the point. Competitive runners wear a Garmin precisely so they don't have to have a phone strapped to their arm. It's heavy, cumbersome and uncomfortable in a race situation. Plus in races longer than 4 hours in length a GPS based app drains the battery and you'd be lucky to have the phone last that long. Garmin devices can be used for up to 12 hour activities. I'm sure when paired with the phone the GPS is fine but if you want the watch solely for running, it is a poor choice. Pop down to any running or triathlon club and the Apple watch is the last piece of kit anyone is talking about.
Totally agree with you. If your are competitive to the point of winning a race (or your age) or want to make money on running, get a dedicated running watch.
If not, I'd say there are pro's and con's to both.
I took up running 5 years ago. Always used my phone, mostly with the Nike+ GPS app. Mostly 3-4 mile runs.
Last summer, I decided to increase distances and get a dedicated GPS running watch. As I read more about AW, I decided to hold off and get it instead. I have not regretted it all.
I'm competitive to the point of wanting to improve for myself. Not to win anything. As any runner will tell you, a Garmin, Smartphone, AW or whatever are just tools to improve. You still have to put the work in and many do improve with no such tracking devises or just with a simple stop watch.
Perhaps the biggest reason for me in getting the AW was for the Fitness aspects. Perhaps the biggest reason for not getting a dedicated running GPS running watch was the lack of value. Even tho I've moved to half marathon distances (and when I meet my half marathon goal at the end of the year, I'll move to full marathons) I typically run 5-7 hours per week. Not much value when a Garmin 220 runs $250ish for less than one day's wear per week.
And since I have kids I love seeing who is texting me on my long runs. Even easy to give a quick reply if really needed. And of course with AW, I'm wearing and using it every day, all day.
I certainly wish the AW had GPS. But I don't think it the end all be all. On my long runs I find myself running the same, known trails/routes around town. And as I'm sure you know, races don't even use GPS to measure the official courses. So it is very, very, unlikely your GPS reading even from something like a Garmin 620 would match, exactly the course.
And as for your comment about what you "others use", I've run in enough half marathons (all of which had fulls with them) and I see many, MANY marathoners using iPhones (or other smartphones). As for seeing AW, it is way to soon to say. You can't even walk in a store an buy one yet. I'd be careful in casting stones. I'd bet when available, running stores will absolutely carry and sell the AW. I doubt will be as popular with your tri club as it is not warranty for waterproofing. V1.0 anyway.
AW will help you as a Garmin fan. As I'm sure you know, Garmin stock has taken a hit and sales significantly down as AW became available. Garmin will have to change, adapt and improve to remain the powerhouse they are. And I hope they do. The in turn will push Apple and be better for all of us.