Quote 1: "My suggestion would be not to weaken your build for RP reasons."
Quote 2: "Again: optimization and role-playing are not mutually exclusive."
If you compare two character builds, there are only 3 possibilities:
1) Build A is distinctly more powerful than Build B.
2) Build A and Build B are approximately equal with respect to power.
3) Build B is distinctly more powerful than Build A.
If you follow Quote 1, you will always choose the more powerful build. When you get to the "most powerful build" level, even if there are "hundreds" of builds that are approximately equal with respect to power, there would be a finite set of builds to choose from. Any time you wanted a gish, you would have X builds to choose from. If none of those builds fit your sense of how you want your character to be, too bad. The only way to never weaken your character for the sake of RP would be to exactly follow one of the optimized builds.
I am not saying optimizing and RP are mutually exclusive, but I am saying following the letter of Quote 1 and RP ARE, at least to a great extent, mutually exclusive. At least, RP would be very significantly limited since your build choices would be severely limited.
So, I have no disagreement with your latest post or Dandu's post, but I still whole-heartedly disagree with Quote 1.