Not being satisfied with a product is not being satisfied with a product, end of story.
Every game dev team works hard to make their own games, Smash doesn't have the right to be treated any differently.
If the character you support didn't make it in,
support them even harder. Don't accept that Mii Costume or Assist Trophy. Make some noise, be as loud as you need to be, vote for them whenever possible, let everyone know how much you want them in.
That's the only way you're going to have even a slight impact on the chance that your most-wanted will get in.
Let the trolls call you, “insufferable, greedy spoiled brats.” They do not give a single **** about your happiness.
After all, Ridley and K. Rool didn't get in by their fans accepting that Ridley was, “too big to work,” or K. Rool was, “an irrelevant, dead, character.”