A few years ago, amidst developing my dry rub for spares, I realized that I had surpassed a dozen ingredients. We (family, neighbors & friends alike) thought it was a really good blend.
In the past year, I have been rethinking what I really want the seasoning to do...I look for what enhances the meat's good flavors and seems to balance well with a particular smoke...I've also discovered that a simpler blend (4-6 ingredients) is just enough to get me there, in most cases. Milder flavored meats don't need much...they already taste good.
Ribs don't have a strong overwhelming flavor which needs to be tamed, and you can't get much simpler than S & P. Toss some minced garlic and chili powder with it, and you'll have it pretty well covered. I do like to experiment fairly often, and when I'm in the mood for it, I'll take a few extra steps along the way, just for giggles.