It takes away from Gimli's role though. Their friendship is a lot more powerful if Gimli is the one who's solely responsible for changing Legolas' minds about Dwarves, which is part of the appeal and greatness of their relationship. They changed each other's minds. Tauriel's influence (or God forbid some deathbed speech about acceptance where she makes him promise to be open to dwarven friendship in the future) making Legolas more open to the idea of Dwarves puts emphasis on her and her role in Legolas' life. But there's no need to give some reason why Legolas is willing to be friends with Gimli -- Gimli is worthy of friendship on his own terms and he proves that. Just being himself is good enough.

If Tauriel places a "germ" in Legolas, then that makes her the first Silvan elf to see dwarves as worthy of friendship, which undermines Legolas' specialness in being able to see Gimli for what he's worth. She's taking Legolas' place in the canon, making Legolas simply a follower of her example instead of someone who's the example themselves.

(I'm the one you replied to but I'm actually not the original poster FYI.)