It's very rare that I need to know about what the weather was like a few hours in the past.
The daily low is the lowest temp of the day. It could very well be in the future. But it’s certainly not in the next day, and it’s not from a specific hour. If you want to see tomorrow mornings temps look at tomorrow’s hourly temps.
Do you expect the daily high to work the same? So maybe at 4pm it’s down from the daily high and now it shows today’s high is actually some temp around 3pm tomorrow?
I get what you’re saying but in no way is that a daily high. More like a next 24 hour high but even then, do you want that? That means if it’s 80F at 3pm today and 90F at 3pm tomorrow and it’s 3pm, then the high will be 90.
It’s much easier to just accurately categorize these by day/hour and let the user find what they care about instead of warping definitions to anticipate certain use cases.