Bull, look at link, probably nintendo's most popular character among gamers at this point and has had tons of players in each installment in the series, and in each installment, he has been mediocre to bad. Popularity does not make a character great, great characters become popular. MK was badass in a few of the kirby games, but do you honestly think he was the most popular and simply became dominant in brawl because more people wanted to play him? what about some of the other good characters like ROB or Pit, think they had huge support beforehand? and here's another thing, a lot of people intentionally play bad characters! I myself have spent more time playing ganondorf than any other character, I'm still better with like 6-8 other characters, because they have much more innate potential. could lower tier characters be used to greater effect than they are typically? yes, you can always try your hardest to hide your weaknesses and emphasize your strengths, become an expert on your character and how to play the matchups with upper tiers, you can overachieve, but you're still going to be overmatched when faced with a player of similar experience to you using one of those characters, and maybe even by a player of less experience than you.