Wouldn't that cut the battery autonomy by 4? Is it really that different having 4K in just a measly 15" surface? (I get it on a 32" screen or a living room TV, but a 15" computer screen?)
Also note the Apple Retina screens were great due to more features apart from just resolution.
Yes. If you use a Retina display for a while, going back is noticeably worse.
Battery life is slightly worse but it’s not linear: the GPU has more pixels to push but usually that’s in a highly optimized rendering path so things like text don’t take 4x as long to render - and on macOS the extra resolution meant it could drop the extra work of subpixel rendering entirely. In the decade since this became common, GPUs and CPUs have become more than enough faster to cancel out the difference.
Also note the Apple Retina screens were great due to more features apart from just resolution.