Just give me one scenario as an example. Maybe I just don't get what you mean.
The imagination is stimulated when you can
not do everything, even as a party. It's intensified if some things can only be done by one class. In NWN2 I remember having played a Ranger. He was, I believe, the only one who could talk to animals or easily identify foot prints. Those things weren't life-changing, but they
were thematic gameplay elements. If I didn't have a Ranger in the group, I'd see foot prints but would have no idea what they mean, or see calm animals that try to tell me something, without being able to understand them.
Something along those lines. Diversity like that is a good thing, because it provides for lots of "what if…" moments. What if I had a paladin or cleric with me, he could turn those undead. What if I had taken
that non-combat skill. I could solve this problem differently.
Having only a few non-combat skills reduces this feeling of diversity and class identity, the
theme. The reason for having so few was, from what I read, that they wanted to make every skill be used a lot, instead of having many that are barely used at all or only in edge cases. Personally I'd have preferred more non-essential or utility skills for more individual flavor.
On the other hand, of course, it's possible to have non-standard sub-classes this way, like an athletic mage who knows a lot about wildlife, which is fine too. Just not as thematic, the latter of which is why there are archetypes in the first place.
It should also be noted that the player's skills are the only one checked in dialogues, so you will probably miss out regardless of how the party is build because you can't invest heavily in all the skills (2 is about the max) on a single character.
That's a good thing, although it also sounds a little backwards and unintuitive. As in: why would party members contribute in combat and wildlife situations, but not in conversations?
