In general League of Legends is a really good game, possibly the best MOBA-game out there right now, but as always, nothing is perfect and even Riot have made a few mistakes lately. A good example is the massive amount of new champions they are constantly pushing out, in a sense it kind of disrupts the general gameplay more than it adds more diversity to it. Appart from that, it feels like they could benefit from another competitive map, yes Summoner’s Rift is a great map, but it was created many years ago for Defence of the Ancients and has since been used in Heroes of Newerth as well, in a sense it’s getting a little outdated.
Anyway, for a long time League of Legends has been in need of a new support champion, and for ages Riot have spent their time making more or less useless damage dealing champions. Well, all of a sudden Lulu shows up, she was supposed to be a support champion but the fact is, she wasn’t, she’s not strong enough as a support while her AP carry abilities are way stronger, she’s even more useful as a ranged AD carry.
Appart from the support situation there are countless examples of how Riot do not really feel like making old champions useful and competitive but instead replacing them with new champions, Xin Zhao is a prime example of this. He got nerfed at one point, then instead of making him useful again Riot decided to add quite a few new melee champions which replaced him, i.e. Talon. There are countless other examples of this as well, Malzahar, Annie and Ashe are among those.
The conclusion here is, Riot are not doing a bad job per say, but they could pay way more attention to making existing champions useful instead of adding a new champion every two weeks, they could add one every two months or so.