People seem to be reading things wrongly, I think.
As much as people may not want to admit it, when it comes to the tier list, the better characters are going to have a lot more debate than the lower characters. There's going to be a much larger debate about G@Ws/Falcos/D3s placements than Link's/PT's/Yoshi's placements, because honestly, the former are more used in competitive gameplay, and trying to deny that is just lol.
That being said, no character should really be any more important than another character, especially when important is such a subjective word. Important to what? Match-ups? The tier list? Your character? Your local tournament? That huge national tourney? etc. etc.
The first post wasn't trying to say, "Well I suck with the low tiers, so they aren't as important." He was trying to say, "Since more people use higher tiers, the SBR didn't put as much time with the lower tiers because in that sense, they aren't as important."
I also don't understand the reasoning for saying, "I main a low tier, I should be more respected because I work harder and am better than the MK mainers, etc." Sure, not many people do that, but some do have a tinge of arrogance because they're good with a lower tier. Sayoing that, "Yoshi is low tier, therefore he doesn't matter," is just as bad as, "Meta Knight is top tier, so he takes no skill and shouldn't be respected."
All in all, people put in way too much weight in the tier list. I don't see why people worry about it so much. Like Youko said on the Brawliversary podcast of Show Me Your News, the Tier List isn't definitive, and it's still debated amongst smash members, SBRers or not. Not every place is exactly right, and you can't say clear cut, "ROB is better than Kirby because he's higher!" I could argue that I think ROB should be lower, Wario should be higher, Zelda/Sheik combination needs to be considered because they work well together, etc., but all in all, why does it matter?
It doesn't matter to the metagame of the community. When a character drops or rises 3 spots, he's not suddenly worse or better. He's the same as he always was, gradually improving or stagnating or whatever, it's just there's a list to show it. The Tier List doesn't have to be exact and definitive, and it's fine as it is, really. Knowing a generalization of where your character is in comparison to the rest of the cast is good enough; after that, work on your character and his or her match-ups. THAT's what matters. People don't realize some of the core things when people decide on where to put someone on the tier list: tournament placement and match-ups.
First, people really need to learn match-ups, moreso past the x:x number. Knowing the core basics is not knowing the match-up. Some people will look at, say, the Fox vs. Peach match-up and go, "Peach can CG me to around 30%, gotta watch out for that, turnips are a pain, but I can gimp her, okay I'm fine," and think they're knowledgable in the match-up, when there's a LOT more to it than that.
And then people need to take those match-ups and see how tourney viable they are, and start placing well in tournaments. Some characters have bad match-ups against like 2/3rds of the cast, and sorry, they aren't as tourney viable when they're that easily countered. Some characters like Fox have 60:40 to 40:60 match-ups on a lot of the cast, but has insanely disadvantageous match-ups against Sheik, ICs, Pika, so they need to pick a secondary to be more viable. Now if your goal is just to do as well as you can with a character, that's fine; go ahead and use that character with the horrible match-ups and push through. But if you're really trying to win and have that as a major goal, sorry, but unless you pick a secondary or just a better character, your chances are very unlikely.
tl;dr: People rely on the Tier List too much. Choose a character that you like and go from there. Don't think, "Oh, he's high-tier, I shouldn't use him," or "Oh, he's low-tier, I shouldn't use him." Choose a character you like and have fun with, and see where they're generally at from there. If they're high on the tier list, great, learn their match-ups. Low, great, learn their match-ups and try to make them as viable as possible.
But honestly, if your character gets hard-countered by literally 95% of the cast, you should probably choose a different character. I highly doubt that out of 37 characters, you only have fun with one.