First I want to say that in most versions the father sneaks into Dame Gothel's garden three times and is caught on the third. I think this is important because in fairy tales often have the number three, for example Cinderella is given three gowns to go to the ball, or Snow White's mother pricks her finger and three drops of blood falls to the snow.
Second is a detail I think is the most important. In the first version of the story that was cleaned up a bit for children, Rapunzel doesn't dumbly tell Dame Gothel that she is heavier then the prince, instead she mentions her dress is too tight around her waist indicating she is pregnant. Personally I think that little detail sheds more light on Dame Gothel's motivation. She doesn't lock beautiful Rapunzel away as a child she waits till she is twelve years old. Which leads me to believe she locked her away from the world when Rapunzel hit puberty out of fear that a lover would take Rapunzel away from her. Also I like to note that in some versions the Prince doesn't leap from the tower, Gothel enraged pushes him from the tower. Because once again I think it makes for a better story then She threatens him and he jumps, instead of demanding to know where bride to be is and she pushes him.
P.S. some ending includes that Gothel drops Rapunzel's braid after the prince escapes trapping her in the tower. Which I think should have been kept in because if the original Grimm's Snow White can have the Queen dancing to her death in hot iron shoes and Cinderella's step sisters lose parts of their foot as well as their eyes being pecked out by birds. I think Gothel should suffer a similar fate. It is Grimm's after all.
I'm sure all these details were taken out to tame them up for the children. But that's what Disney is for. Don't get me wrong. I love every version. However as an adult I like the originals to stay dark. Maybe not as dark as Sleeping Beauty because the first version of that is just horrifyingly disturbing. However I think the original version of Rapunzel makes for a better story then the cleaned up versions. Maybe I'm just extra picky because it's my all time favorite fairy tale.