You know, I partially agree with you. Hypixel has a really distinctive style and it's really.... cool, simply put.
Cube on the other hand is really minimalistic and simple, and considering how common it is to come by minimalistic art for web design I'm not surprised it probably doesn't fulfill everyone's expectations.
What I think is Cube should develop more of an own style. It's just really plain, minimalistic can be done well, it has been done well and it will always be possible to be done well, yet Cube is the standard XenForo forum... The only thing that gives this website a "graphical face"? The banner on top, with the logo and the screenshot. That's it.
I think some texturization could go into the mix, like adding various shape patterns on the individual boxes, and some background work. As you can easily see, the background is just a white background, with some lines of various shades. That's a style that should be more appropriate for the individual boxes, and then an image for the background, in this case I think screenshots from the in-game network could be the thing you're looking for.
I have made an example for the boxes:
View attachment 130517
It's just a bunch of lines with a gradient thrown on it. Now, that design can be greatly improved, I've kind of slacked it, had stuff to do, heh
But yeah. Cubecraft doesn't have to be so simple. It's time to get a face, a style.