What if riot removed flash?

Of the five roles, four of them have mandatory spells that are always taken. I just read a post that said only mid laners get to choose their summs, which is sadly true (confirmed by a rioter). Even then, flash is taken on 95% of champs at all times.

If riot removed flash, maybe we would see new spell combos that would be more unique to every type of champion. All flash does is give everyone in the game a free USE THIS BUTTON TO MAKE PLAYS/FIX MISTAKES which feels a little bit binary and too useful for every champion. If your flash is down, you are forced to play defensively or safely. If it's up, you will be playing more aggresively. When you lock people down, you don't get rewarded for effectively cc'ing them because they can just flash away. It makes flash too valuable for every champion.

Without it, it would be interesting to see what summs each champ would take. Ahem TP Ahem. Either way, it encourages variety to the game, something summs have really lacked in for a while.