Years and days are fundamental units that you're kind of stuck with because they're so fundamental to life on earth. But, even though seconds are SI units, there's nothing about them that's special. They're just a holdover from dividing a day into 24 units, then those units further subdivided by 60 and then another 60.

What's interesting is that the metric system was invented at a time when being able to convert between units in a way that's easy for the human brain was important because technology was advanced enough that things could be measured precisely, but wasn't advanced enough that computers could do the conversion for you.

What's interesting is that now, before Metric has even caught on worldwide, we're already past the point of needing easy conversions. The Metric System was important when it was invented because technology had advanced to a point where precision measurement was possible and important, but computers didn't yet exist. So, converting between miles per hour and feed per second was a pain. But, these days everyone has a smart phone, smart watch, voice assistant, etc. nearby that can easily do the most gnarly conversions with ease.

I'd still like metric time units, but tradition might win over logic now that Apple Watches are so common.