Since when did we want a Sandbox mode?

As long as I can remember posting on these forums people have been asking for a place they can try champs and skins and stuff before they buy them. If that's what you're referring to... then at least 3-4 years.

http://boards.na.leagueoflegends.com/en/c/summoners-rift/iVtpIvhg-new-game-mode-introducing-practice-mode

I was most certainly not the first to suggest it, either.

http://boards.na.leagueoflegends.com/en/search?query=sandbox&content_type=discussion Ranging between 1 month ago to a year ago. I'm sure there's some more in the forums, too.

Since Dota 2 had a similar thing (especially through console commands afaik.)

People always want something more and hate being told no. Very few people actually want it but everyone is throwing a fit cause they heard no.

Honestly i think people need to focus on what riot is going to change and all the implications it has for the game.

Since StarCraft 1.

I know I made a post about it ages ago, how we needed a more customizable custom mode. I didn't call it a "sandbox mode", but it was the same idea.