Question:
This is the trend I've noticed: Users: We want X. Riot: Doing X, Y, and Z is challenging/not what you want. Users: We just want X, not Y and Z. Riot: [silence]. Do you agree with this assessment and see how that's frustrating to players? See HUD customization and sandbox mode for examples of this.
Ask.fm doesn't allow you to edit answers, but since I used a poor choice of words, and since not everyone is seeing my follow up attempts to clarify my original point, I am going to just take a shot at rewriting the answer. I included the original answer below to avoid any perception that I am trying to cover it up.
NEW ANSWER: We want to deliver to you the things that you ask for. Sometimes we'll design or implement them in a different way because we think we've figured out a solution to deliver on what you're asking for in an even better way, but goal is the same.
What I originally thought you were saying (and which you have since clarified was a misperception on my part) was that we should only be working on the things that you ask for. Part of what we want to do is deliver things that you didn't even know you wanted but hopefully get excited about. Things like Bard, Black Market Brawlers, the Jinx video and Champion Mastery were things Riot got excited about doing because we hoped you'd like them, not because you were on forums demading them.
Many developers (including me) make the mistake sometimes of saying "You don't really want that," and that comes across as patronizing. It's on us to prove to you why the stuff we are working on is worth working on when you get to play the game and try the stuff out.
The [silence] part has been tricky. We've erred on talking about things too soon and we've erred about not talking about them enough. We have currently been talking a lot about what we're going to do about that problem. Maybe the right answer is to default to transparency, tell you even about the long-term bets we've invested in, and hope you don't get discouraged if the wait is long.
ORIGINAL ANSWER: If you only ever give players or customers exactly what they want you lose all chance to surprise or delight them with something unexpected. Games are supposed to be fun and that sounds like it would lead to something pretty predictable and maybe even boring.