You are correct, they do, via the official keyboard/trackpad case. Or you can even just connect any other bluetooth keyboard+trackpad (including the dedicated magic keyboard+trackpad for macs). And most of the keyboard+trackpad shortcuts/gestures are already the same on both macOS and iPadOS
Just because it hasn't been updated in forever doesn't mean it needs to be. I get the feeling that people get bored with a design and expect a design refresh.
It hasn’t been updated and was really bad. It made sense back in 10.2 or so, but now every preference pane has tabs and buttons for modal dialogs and stuff. It needed about twice as many panes for each one to be manageable, and the icons palette does not scale that far (it’s actually quite confusing now on Monterrey, where all icons are very similar).
The new one is not perfect. For example, the on/off switches are ugly and the layout is far from great, and I like “preferences” better than “settings”, which makes more sense for an appliance than for something you adapt to your liking. But the old one was very much not “not broken”.