Mobility Items

So I'm a huge fan of both LoL but Dota 2 but I have always felt at a loss when it comes to mobility in LoL (while the dota 2 map is much bigger and I understand this I just never understood why Riot isn't a fan of mobility and I don't mean in terms of movement speed). When I say this I am speaking about both blink dagger and force staff in dota 2. My biggest issue is that flash almost always must be taken by nearly every hero bar a few because it just allows for higher chance of survival in terms of offensiveness and defensiveness. I guess my opinion is I would like to see flash replaced with an in game item that a player could buy. I think it would force players to make a decision as to whether or not they want to go for this item that may save more or if they want to just go full out and not worry about it.

The other possibility that I was think would this could be added to boots in the same sense of Alacrity and Homeguard and so on. It would cost mana to use.

I think it would allow for interesting plays to be made and could be fun to see what could happen. So what do you guys think would it be interesting to see mobility style items in the game?