It's not the size that counts, it's what you do with it. There's little to do on planets regardless of size.
In a thread called "really large landable planets: the list", it's gonna be the size, yes.
You are of course completely free to create a thread called "rant about lack of stuff to do/shoot at on planets". In that regard, I'd advise you to find something original with the title, as there are already quite a lot of those on the forums. In short, if you're gonna rant, this thread is not for you, so pretty please don't derail it.
There are a lot of folks enjoying the fact that they can explore even further with planet landings, and find unique things in the galaxy, mind you. Landing on a planet four times bigger than earth (the current record holder) is quite a thrill. And not a lesser one than shooting at stuff. I, for one, enjoy fighting, trading, exploring, and the contemplative side of it. It makes me really sad (to say the least) to see the forums state right now. What ED made with Horizons, and the way they did it is nothing short of extraordinary. Many of us enjoy it tremendously, while understanding that others may not. That's about it.