In time, Apple may change this and allow them. But with exposed functionality, start with a minimum viable product. What you add you can't easily remove.
My Moto 360 lasts all day and has all this functionality and neither Google or Motorola has been sued by anyone. Its weird how people will excuse Apple with made-up assumptions instead of the time-tested "rushed product" conclusion that is more often true than not in the tech industry.
It larger as it in has a larger screen which draws much more power. Not sure where you are going with this. There are AW watches that are smaller and last all day also, and then some. LG G watch, Zenwatch, Gear, etc.
A bigger battery generally more than offsets a bigger display (see the iPhone 6+ getting better battery life than the iPhone 6 even with a larger display). All of the watches you list are still larger than the largest Apple Watch.