I've struggled a bit on your 3, 5, and 6, but ultimately decided to get an Apple Watch. Here are my thougths/responses to your issues
1) iPhone Requirement
But you already have an iPhone... so surely that can't be a reason why YOU didn't get one. Sure I think Apple may be limiting their market, but in the end, I think this decision will gain Apple more profit (by switchers from android to iphone) than lost (from people who would have gotten an Apple watch, but didn't have an iPhone).
2) Lag
Most of this lag is from 3rd party apps which run on the iPhone, rather than an issue with the apple watch itself. This will likely change later this year with full-fledged apple watch apps.
3) GPS
I agreed with this for a while... but I have come to settle on this being a good decision for the moment. It's obviously a battery compromise (which is another complaint of yours). I feel fine about this because I can either a) bring my iPhone, which I would likely do anyway to get full music, data, audiobooks, podcast... or b) not bring my iPhone and therefor not get GPS data, but still get a surprisingly accurate distance due to calibration.
4) lack of purpose
I think one of the bigger complaints is the lack of focus, which can be argued as "too much purpose" (i.e. you can pick from whatever purpose fits you). This is "apple's most personal device ever" so you can decide if you want it for fitness tracking, for notifications, for glancable information, etc. There's a lot you can do with it, just figure out what works best for you.
5) 2nd gen is better
Well... yeah... I waited for second gen iPhone/iPad. I almost waited for second gen Apple watch as well. But I ultimately decided that this radically different product was too exciting for me to not be one of the first to test it out during the "beta tester" phase.
6) battery life
Most people seem pretty happy with a full day of use. If you are expecting 2 day battery life, that just isn't going to happen anytime in the next 5 years. 2nd gen may have incremental improvements, but it's certainly not going to be a selling point. Especially if they add GPS like you're wanting