To be short if you don't want to read all of this: MVPing does require skill but is constantly overshadowed by PVPing. Rather than assuming it takes skill, I just consider it as a source of being "Great".
MVPing does in fact, prove a certain amount of how "Great" you are. How? Basically in my view, MVPing takes skills as you need to know how to counter the MVP with your given options of equips, class, and skills. With that held in mind, you must make use of them and plan a tactic that will allow you to take down an MVP by yourself. If you can solo, say, Ifrit, by yourself without having to struggle too much against it, then you are certainly "great"... at MVPing.
Of course, having a party to MVP does not hinder your status of being "great". In fact, it supports it. It's shown that you're great if you are capable of helping your party and being an important aspect of the team in defeating the said MVP.
Though, just being capable of MVPing by yourself or with a party efficiently, only conjures about 1/4 of how "Great" you are. Reason is, there are many popular ways in defeating an MVP that doesn't require much thought. Thus, for that lost portion, it is made up through sheer sweat and blood by killing other players in PVP.
Sadly, majority see PVP as a system that determines if you're pro or not, therefore, MVPing isn't valued as much and is masked underneath PVPing to the point where PVP completely determines whether you are great or not in RO.
I forgot to mention that MVPs to me are the source of achieving "Greatness"! Simply because I tend to MVP early on before hitting level 70, thus, I end up with equips and part of the economy on my account. I also hog the MVPs for the cards.