Because they are still room for more buttons on the interface.
and because 4 is not enough, 8 would be cool for me.

One for each outfit? I thought you only had the one....

+1

In the meantime, there is SLM, which can actually be more useful in some ways (per-station presets, for example, as well as coloring the button text based on the preset ship color).

Just make the presets be a unique set by station

No. Global presets are also useful, so you don't have to define the same ship over and over.

Then we need more. And how about the ones not available at the station you're at are greyed out?

Now that's a good suggestion ^

Make sure it factors in your station inventory too. I have a bunch of presets that rely on a stockpile of addons.

4 global
2 local
1 nonexistent teasing you about a cross faction ship you can't have.