Perhaps I should watch "Pen Pals" again, but based on memory and the synopsis on Memory Alpha, there is a significant mitigating factor.
At first, Picard (and as the Commanding Officer, his is the only opinion that should matter) does not want to interfere; the same stance he takes in "Homeward." However, the direct plea for help (played by Data) can be considered something different, and the Enterprise should intervene at that point. Picard's justification is "Your whisper from the dark has now become a plea, we cannot turn our backs."
All in all, both episodes show a basic reluctance to violate the Prime Directive, but exceptional conditions (Data playing the direct plea for help, Nikolai Rozhenko beaming up the villagers in 'Homeward') cause the crew to take action, more or less willingly. I consider the crew (and Picard's) attitudes towards the Prime Directive to have changed that much.