Yeah, of course it's a cost for SBS. I also though about that, but in the end that's something they have to decide and I don't really have to care about. Since I just want to give a suggestion.
I really think about one big puzzle which is not solved within a year. It also shouln't be tied to any skill really. Maybe the runes just unvold a story. Like story written down on paper. "Once there was a men, he fought the dragon. End"-kind of thing. Maybe it allows you some very little advantages, like aging not that fast or whatever - that doesn't really matter.
If I could design the puzzle, I would really go with deciphering runes. Like the egyptian symbols. I would you invent some encryption algorithm. A very very very easy example would be https://en.wikipedia.org/wiki/Caesar_cipher and then just spread these runes-sequences around the world or whatever. You don't need any interface where, you don't need to just find enough and your avatar somehow makes sense of it. The point of it should be that you sit down, write them down, and just star at it for a few months, trying to somehow solve it. And suddendly, you can, by hand, translate these rune-sequences.
You should gain some wisdome (which should not be crucial to the overall game) out of solve this. It should be hard, so you don't want other people to gain it. Causing conflicts.
Some of you might think about some little oblivion style puzzles. That's not really what I meant.
I just like the idea of some independent monastery where the people master all the skills. And such a puzzle kind of thing would fit that very well. (And since this is probably a more nerd-oriented game g, I guess, there are a lot of people who would enjoy it). I just like the idea of somehow "hidden" knowledge. With in-game mechanics, everyone sooner or later kind of is shown that knowledge. With something like I meant, that might (might!) not be the case.
But yeah, it might be just too much work for a too small audience. But as I said, that's not really for me to say. I actually don't really belive in it, since it's a small team and so on, but I just wanted to share the idea. :)