The problem is, aiming to create a "high-end" product up front ends up shaping the product design. Now that it is aimed at the high end, Apple needs to include

The problem is, aiming to create a "high-end" product up front ends up shaping the product design. Now that it is aimed at the high end, Apple needs to include lots of features, a nice display etc. Lots fancy features means they need to use a powerful processor, which along with the nice display leads to a lot of power draw. This is why they have a small battery life, as you mention, and didn't even have an always on display until S5. Neither of these are technological constraints, since the Pebble had 7 day battery life with an always on display from the first version. Now, the Apple Watch has sold well, so maybe it's a fine tradeoff to make. But I think this "high-end" constraint has definitely shaped the product (and in a way I think is worse when viewed as a watch first).