After some research, I suspect the answer is:
- We do in fact prefer more daylight during evenings in summer. Because of this, we might prefer permanent DST.
- However, we can only borrow the evening daylight from mornings during summer. In winter, there's no light to borrow, unless we want mornings to be black.
It appears that permanent DST would be great for those of us who get up late (more daylight!); but it would make winter mornings dreary for people who need to be at work or school at 8 am or 9 am.
Conversely, permanent standard time would make summer evenings end early, and in exchange we'd get the sun waking us up at 4:15 am.
It follows that there is wisdom in the current arrangement, resulting from forces of nature. sigh
Interestingly, the British did try permanent DST from 1968 - 1971. Apparently, mornings were dreary. Though note that Britain is further north than most of the US.
Russia – even further north – also tried year-round DST in 2011, but moved to year-round standard time in 2014 after people wearied of dark winter mornings. And in summer, their sunsets are at 9 pm, anyway.