But what does reclassifying what a planet is help?

Reclassification becomes necessary when our thinking (or models, if you will) on a certain subject cannot jive or be sustained given the new findings. (Re)classification is going on all of the time. There is already substantial resistance to it since doing so means rerunning potentially thousands of experiments and rewriting a very many papers/textbooks on anything involving it. Imagine how many things had to be rewritten/done when Einstein's theories were verified!

Let me be clear that there is no classification for its own sake going on. The sheer amount of work and potential embarrassment involved if your findings are unsound is enough to keep most people in the scientific community from doing virtually anything trivial.