Quit taking away featured game modes

I understand that a lot of the hype about featured game modes comes from the fact that they are a limited time thing.

Here's my thought though: instead of removing the featured game modes in the entirety after the time period has elapsed, why not allow the players to have the featured game modes as a game mode option when creating a custom game?

This wouldn't be splitting the matchmaking que up, which is often the argument people have for as to why the featured game modes are limited time.

Maybe Riot uses the featured game modes in the same fashion that a department store uses clearance sales, wherein it brings more people in for a period of time? I'm not sure. But, as a regular player, I feel like in some cases things are catered more towards the on-and-off player who comes back just for URF.

Maybe part of me feeling this way stems from the fact that Dota 2 has no restrictions on their "featured" game modes. Maybe Valve is just more capable than Riot in this aspect? Again, I'm not sure. I just wanted to express this idea, as I didn't really see a downside to it (albeit I'm not a technical expert, and who knows it may be too much stress on the system).