You love ze beetle?
I know Thumbelina gets a lot of flack for its messages, but I think some people try to read too much into it and are looking for ways to twist what is actually being said.
I absolutely love the scene with Jacquimo and Thumbelina after she gets away from the beetle ball. Thumbelina tells him how the beetle called her ugly and Jacquimo asks if she loves the beetle, to which she replies something like, "No, I love Prince Cornelius." Jacquimo asks her if the prince thinks she's ugly and she tells him that he doesn't, he actually thinks she is beautiful. So, Jacquimo points out that it shouldn't matter what the beetles think.
The Prince loves her and thinks she's beautiful. If that makes her happy, she shouldn't worry about what anybody else thinks. :)