actually you get the shrine bonus when u defeat the hero in royal challenge for the first time not when u recruit them.
If u are never going to use a hero, I wouldn't go back and try to win them, this is especially true of the purple heroes because there is not the same need to get them built up to transfer to newer heroes(or at least we hope) and there are so many that the chances of winning a purple hero card you actually use is already small enough.