I think you guys should have more faith in some of your older designs; they have their own merritts. Many of your older champions can be played in a variety of ways, or took a little bit for people to realize their potential and power. Nowadays, the new characters just seem to scream OP BBQ WTF, and rather than being played multiple ways, are just given so many tools that they are just too powerful (like Graves). This is all happening while you guys tend to nerf some of the older champions which seems to really making accepting the nerfs and seeing the new champions rampage a lot more noticeable
That said, I think the focus should be to get more counters, or have a different approach to the way you guys go about your buffs and nerfs. For example, I think nerfing Soraka AP ratios was not the right thing to do if you want more aggressive lanes; rather than that make her bases worse, but give her maybe better ratios. This gives more options as to what items she should be building (auras vs AP) and also lessens her strength during the laning phases for both solo and duo. While I feel like you guys did probably test this, you guys may have come to conclusions that only the actual player base can determine, because there is such a larger sample size.
These designs are bad for the game if they're strong, but when they're balanced they really have the satisfaction ripped out of them. A character who's job it is to slowly heal people up and provide sustain only makes the game more weak - and the gain is that healer archetype players get to have the character they're used to in other games (the TF2 medic is the most shining example of this problem in action).