You were complaining about it being too heavy when holding it with one hand. Make up your mind. If you're going to hold it with two, hold it with one hand in the center and one hand in the corner.
It's not rocket science.
That's my whole point. A 16:9 device is awkward to hold, especially if the device is heavy like the Surface is. Perhaps MS will be able to do something in software to compensate for that sensitivity.
My point is that if you hold it in the corner, it's going to be too heavy even if it's a square. Your complaint about the aspect ratio is irrelevant at that point. You should be complaining that the Windows button doesn't allow you to hold it wrong.
That's a pretty narrow use case. As a mobile device, I very rarely reach for the Surface because it's not nearly as convenient as other tablet options. And a few times I have reached for it, I have regretted later because the batter had run dead. If you leave it in standby for more than a few days without it being on the charger, it'll be dead. Never have that problem with the iPad, but on more than one occasion I've arrived with my Surface only to find it completely drained and unusable.
Reach for it and do what with it? Walk around the house with it? 90% of the use cases for any computing device is while being seated, especially with any tablet that you can't palm. At least with a 16:9 device someone with larger hands could palm it in portrait mode. It'd be far more difficult to do with a 4:3 device. That's why Apple made the iPad Mini, because the 9.7" is definitely not intended for one hand use.