Well for the first part, about Chara tee development, I do that same thing all the time. I love thinking exactly how my character will function and what he'll look like at the end and how I get there. Now I don't think random dice affect this planning, but I'm not exactly sure how you think it does? I'm not trying to be cynical, I'm just not fully understanding what you mean.
I think the dice can have an impact on tactics however. I have to agree that parties of four tend to create more jack of all trade characters, but I think it's still somewhat possible. I think we'll have to wait and see how dedicated roles can be when ea comes out, cause I'm not sure.
The interaction between character development and dice randomness is in the extent to which how you developed your character is what determines outcomes (including in combat), versus the dice rolls determining those outcomes. Now obviously this is not absolute (i.e. not black and white/either or). D&D for example obviously does include character development. But for my tastes, in D&D, how you choose to develop your characters doesn't matter enough while random chance (the D20 roll) matters too much. I want my careful planning of my characters and my choices in their development to matter more in outcomes (in dialog, in skill/ability checks, and in combat) and the D20 roll result part to matter less. So it's a balance thing. For me, the balance is too much towards the D20 roll in D&D. By contrast, if you look at the PoE system, for me that is awesome because your character development choices matter more heavily and the die roll's impact on outcomes is much lighter/narrower.