Oooh, I like where this discussion is heading.
Someone mentioned having static, or mostly static attributes. While I support this decision in principle. I think it does leave something out of the idea that "today a wizard, tomorrow a battlemage".
But if stats were more meaningful (and weren't all over every piece of equipment) than even getting 1 stat every few levels could work. The key is 'could work' I think we can all agree from playing all the forms of RPGs over our gaming careers that a lot of different systems 'could work'.

So would it be a fair direction to instead discuss what the goals of a system that works would be?

I propose:
1. That the system provides an avenue for a wide range of effective builds. (this is the biggest draw of the original sin series and it's most unique aspect when compared to similar games. You have no restrictions, class or otherwise. Many of the stat systems mentioned in this thread for comparison exist in rpgs with more rigidly defined roles)
2. That the system makes apparent sense and is intuitive. (strength for the strong, con for those who take many hits etc.)
3. That the system is fun to use. (this also covers progression and level-up, for instance: a static system takes some of the fun out of leveling up and developing your character, you make less choices and you cannot change your decision after the fact.)

I think the current system:
1. Moderate success. I think as awkward as it is, the current system allows a wide range of effective builds. I finished a play through with a battlemage (war/pyro/geo) who wore a staff and slaughtered lots of bad guys. My stats were also a nightmare (I purposefully just threw this and that there) and it was still a relatively easy clear. However, the current system also has too many dump stats and conversely: ideal stats. Limz might have more to say about this as he'd tried more builds.
2. This is where the biggest failing is. One, because it confused most players and even many critics and two, because all some of them do is tweak one maybe two numbers right now, and not very convincingly.
3. I think this is also something that could be improved currently. I mentioned earlier that I barely cared about stats unless it was memory. And I made a completely effective character by putting every single point into finesse and using only 3-4 skills the entire play through.