I'm going to translate your post.
"I don't know how to play certain types of characters and I just can't get the hang of them. However, instead of acknowleding that fact, I will blame Riot for not accomodating my individual needs. Clearly if I don't know how to play a class of character, there is something evidently wrong with that class even though there are thousands if not hundreds of thousands of other players who excel while playing those characters and do remarkably well with them; such as a certain handsome and charming fellow by the name of Umiman."
I might have read in between the lines a bit. Oh man, I would prefer it if you were right though. Then that would mean I'm a ridiculously incredible player for being able to regularly dominate while being a useless support which does no damage, can't tank, and is always mana-starved. Pffft, two weak heals too. Who would ever play such a useless character? Oh wait, I AM a ridiculously incredible player. Phew... made me a bit worried there.
I can play any style of character and do well. I don't really think I have a specialty. I usually pick last to see what my team needs and then just hit random until I get a character that fits the role. The only two characters I don't play are TF and Soraka, because I think they're incredibly underpowered currently.
I also don't think there's a single character in the game that doesn't do well under the right circumstances and with a good player supported by a good team. Best teamwork ultimately wins.
However, there are certain characters that are innately less versatile, weak by the numbers, and all around less effective. All other things equal, these characters are at a disadvantage against others. And yes, Soraka's heals are weak. Alistar and Sona's heals are weak, but spammable and low mana cost. Taric can heal almost anybody up to full from nothing in one shot late game. Just from what I've seen in-game, my impression is that Soraka's heals are about equal to Nidalee's, except she has two of them and one global... and she's one of the most mana hungry characters. My wife mained Soraka for months, and not much about her has changed since then.
I also didn't mean to say that dps carries are useless. They are incredibly dangerous snowballers. Feed a yi, gangplank, tryndamere, xin, any ranged dps, etc, and the effect is more drastic than any other type of character getting fed. The dynamics of the game are just designed to be stacked against this happening. So you end up with a bunch of characters who are always either completely worthless, ridiculously powerful... or focus on being a minor nuisance with a frozen mallet. I just don't like this flick-of-a-switch style balance.