Too many "slow, safe games" isn't all that exciting.
Riot has detailed a number of changes coming in updates 8.4 and 8.5 that they think should spice up top-level League of Legends matches. The studio pointed out that regular games are nicely paced, but recently there's a trend emerging in pro games whereby the action is too "slow" and "safe", making the game less fun for spectators.
8.4 is getting a number of tweaks which Riot hopes will mix things up a little, and plan to remove Tracker's Knight from the jungle items and increase the potency of Epic monster buffs, among other things. They're also looking to make tweaks to Ahri and Quinn in the near future, which you can read in more detail here.