If you want certain outcomes you have to select Paragon or Renegade throughout the entire game more or less to make sure you have enough points later. Paragon/Renegade dialogue and interrupts are always the 'optimal' pick when available. The problem isn't the P/R options themselves existing.
It's good to have both goody-two-shows and more morally grey options for resolving big-picture conflicts and smaller-scale convos. Paragon and Renegade are fine for roleplaying options.
