Why is Riot so slow? Because...

They want to make sure they are releasing something as functional as possible and nobody but Riot knows the difficulties it comes with.

I'd like to share to whom hasn't come across this post an answer from Riot Lyte regarding the excessive amount of times people say stuff like "Why is Riot so slow?!", "What's so hard?". - Find it here.

I so very much agree with him, way too many people harass the developers with these question. You don't know what is involved in the process of development of this game, hence what gives you the right to say that Riot developers sit in their office being lazy? Have you been to the Riot offices? Have you ever developed a game? Have you ever managed an office as big as Riot's? Have you ever left your room to process information to back what you are claiming? - If the answer to these questions is 'No', and I'm pretty sure it is, just think before opening threads and harassing Riot developers - "Don't do to others what you wouldn't like to be done to yourself" - Isn't that something everyone should stand by?

Be more understanding, nobody likes to be harassed, don't be the one who harasses.

Also find more answers on the matter here