Actually, this is false. Jiraiya's appearance when he entered Sage mode is he never got the chakra balance perfect, so he entered an Imperfect Sage mode. Naruto's eyes transforming alone was a sign that he had the chakra balance perfect. Jiraiya fusing with Ma and Pa was only so that he could keep using Sage mode by having them draw in the sage chakra while he had to move. Naruto got around the inability to do that by using his shadow clones.
First of all, didn't Jiraiya need them in the first place just to go into sage mode. They were the ones that helped to manage it but as a result he entered a partially transformed state because he also merged with two toads. The same is also evident when kabuto entered sage mode with the snakes attached. His appearence was also very snake like. Then there is the fact that you need the animals attached just to be able to gather sage chakra while moving. Naruto can't do that because he has the kyubi which is why he has only a partial transformation where he gathers just enough that he can manage the chakra but he doesn't have the full sage ability to gather chakra while moving. I think orochimaru is in the same boat which is why in some cases you see him standing still alot until he wants to use those high end abilities of his. Then when he needs to gather again he stops and waits while gathering.