OK, challenge accepted.
let us say I ever want to make either a chemistry station or an auto turret, for that science 7 is required so there go all those levels of advancement. Now personally I always prioritize armor, the less damage I take the better it is for me, regardless of how I choose to engage zeds. So there go 2 of my main choices. 1 made to provide antibiotics and one to mitigate damage. Now true,there are no items that I know of requiring science 10so fine...I get 2 other choices to raise to 5 and another to only level 3.{and yes I know a chem station isn't required to make antibiotics}
So now at best my melee can hit say level 8 just to use those 3 extra ranks, that leaves me only 1 other choice to raise to level 5, tool smithing and gun smithing come to mind, not even considering the oddballs that only require 1 or 2 ranks, the workbench, the aforementioned chemistry station, concrete mixing, or steel smithing. By no means do I feel the need to max everything, but unless crafting and combat are sepperated then the options are too limited for long duration play.
I have logged more hours playing than I care to admit, and for a long time now when I die, that is all she wrote, delete and start over. If we are allowed to respec then my arguement is definitly invalid, as then should you decide to go another route you can, but setting in stone a given build is going the wrong way. I would reccomend looking at the system used by UO way back when with a system that raised or degraded over time depending on what you were doing.