This "Tiers" list is what I have a problem with. This should not be taken seriously, it's just fans categorizing characters and scaring people into not using so called "Bottom Tier Characters" just because of certain flaws that don't really affect gameplay much, if not at all. Sorry but it's all down to how you use the character, not stats. Seriously there are people out there who use the weakest characters (Before you say, I am talking about weak in general, not based on Tiers) but still manage to beat even the best of the best.
Actually tiers mean EVERYTHING... They are a part of fighting game science. Tiers are based on extensive testing and experimentation. This might sound silly, but there are gamers out there who take this subject extremely seriously. Don't get me wrong, however, there are fringe tier lists out there that are biased and essentially rubbish, but the legit ones are worth noting.
Conversely, I agree that there are gamers out there who are total beasts with the supposed "bottom-tier" characters. I like to refer to said types as...well...gifted. They apparently put a lot of time and effort into the using a given bottom-tier character's few strengths effectively and/or otherwise turning said character's weaknesses into strengths,
per se. This usually involves the use of "cheap" tricks and things of the sort. Bad matchups tend to become irksome and lengthy because of this, but hey, at least the "bottom-tier" guy comes out on top (rhetorically speaking).
The [legit] tier list serves as a base off which to select one's main and sub characters and participate competitively against other gamers. After consulting it, it is then up to you to decide which character best fits your fighting style. If a given character is low on the list, then that gives you an incentive to work harder to master him/her. In the end, however, it is up to you whether to take them to heart...
But remember, S-tier characters can be terrible in the hands of a "n00b." This typically results from the steep learning curve with which said characters are often associated... ramble...ramble...ramble.