1. Kirby is not flawless nor a Gary Stu, otherwise Galeem would not have been able to "kill" everyone in front of kirby without dying first to to the pink puff. Kirby is also been proven to be very easy to manipulate, curse, and steal from. Sure he does destroy the bad guy in the end, but not after a long chase/quest with usually some help from friends/enemies.

2. Kirby did not escape Galeem due to his own merits but rather due to his warp star which has been proven countless times capable of traveling to other planets in a matter of seconds. His weakness was shown very clearly there: he didn't have enough capabilities to survive the beams and will clearly need to rescue his smash friend and rely on their help and the power of spirits to take down Galeem.

3. Smash bash memes are never appreciated. People worked hard and took time out of their life to make this game a reality. One small detail such as a character not getting in or not getting enough of the spotlight won't change the end result: it was made for enjoyment,people will love it and then will probably ditch it when the next one comes along if it ever does.