If you tell me that it’s May 10th, I have a pretty good idea of what the temperature is likely to be, what plants are growing, which direction the length of days is moving, etc. Likewise, if you tell me that it’s Spring, I have a pretty good idea of all of that as well but, yes, we could get away without having the seasons and just use hard dates.
Would you prefer to throw away the concept of seasons? Does it add anything that couldn’t be made more precise and mathematical?
For length measurements, there was no one standard decided and people were fine to get rid of the old systems. But with the clock, we decided how to split things based on what was the most convenient for our way of thinking about the subject, how long meetings last on average, and so on. We ended up with the 24 hour clock and divisions of 60. The decimal clock worked just fine, mathematically, and people could have made meetings that were 2/5ths of a decimal hour, if they’d wanted to, but having to deal with bizarre time slices like “2/5ths” was annoying and they tossed it because it was too far removed from the human experience.
From a purely rational and mechanical standpoint, though, the decimal clock would have tied in perfectly to the rest of the metric system and we failed our rationality test as a species by not migrating to it.
Fahrenheit is the same. With it, you get nice temperature slices that work for us. 0 is dangerously cold, 1/4th is snow, 3/4ths is perfectly comfortable, and 4/4ths is where things start to get too hot. Without it, you mostly deal with numbers that aren’t appealing and seem to have been randomly attached to everything.
The rational system is more useful if you’re a number cruncher, doing science. But that’s true of almost none of the human population. For the other 99%, they like seasons, a 24 hour clock, and would probably prefer Fahrenheit.