Yes, I am thinking along the same lines. I understand the general point about specialising and it does seem the most sensible approach after a certain point, but right now…
For example, a point can be made that he is specialising (as Olinser put it) in mêlée combat (well, at least a combination of mêlée and ranged combat, as bows are formally defined as ranged weapons, I think), but maybe this is less a conscious choice on Jee-han's part than a trend due to the fact that he has met mostly zombies who are best dealt with this way (are they normally, in games?). However, he is also a healer, and maybe that skill will play a greater role in the future. The authors often make the point that as "The Gamer", Jee-han doesn't have some of the limitations of characters in actual MMORPGs, who are locked into classes like "warrior", "rogue", "wizard" and "healer". Jee-han was himself puzzled by the fact that there doesn't seem to be a limit to how powerful he can become, be it in attack or defence.
There is also the fact that the other ability users do not follow the same rules as Jee-han. Contrarily to him, they cannot decide to become stronger or cleverer with the same degree of freedom. So it is possible that Jee-han can, at a certain point, become so powerful that even if he is balanced in his skills, each of them can individually overwhelm the ordinary foe. His ability class is Shinin, which is supposed to be very rare.
Also, he doesn't have a guide or standard of comparison, so the only way to test the consequences of his stats is to increase them. I think that the best moment to do that is now, when he is not so powerful that he will attract other users' attention, and can test his skills on harmless zombies. He can specialise later: it doesn't seem uncommon that acquired ability users reach levels in the 60s or so, so there isn't much of a problem in using a couple dozen points in each skill (he would need only a dozen levels to cover the waste) right now when he is weak and see what kind of benefits ensue. For example, would his craft skill improve with his dexterity or intelligence?
I would also make a point that becoming too strong, clever or lucky might create problems with the Interference Law.