I mentioned in another comment about how I had the Pebble watch (before Apple and Android watches were a thing) and it had 128 kb ram total, but it lasted 11 days. That thing was a beast, but as someone else mentioned cost is a. big consideration too. It had 150 mAh on the newer models, before it was discontinued, so while I'm sure it definitely eats up energy I think it's definitely possible to fit more RAM in the power constraints.
Granted that was an e-paper display. (They had color and black and white options)
Granted that was an e-paper display. (They had color and black and white options)