Top Lane protection came when Riot was tired of teams doing 2v1 bot and top to take the first towers down quickly and accelerate the game. So they wanted to force the bot duos back to bot. The protection has always been more of a band-aid than an addressing of the fundamental cause of why they did it to begin with. Riot put themselves in a tough spot when it comes to the design of League atm. They want faster games, but they also want to keep players from being alienated from what they know, so they keep a lot of stuff intact for the sake of keeping the damage down (not in game damage, I mean the damage or pain of having to suffer drastic changes).
I feel that League or at least their design team needs a big brainstorm on choosing what to do with League cause right now, SR, their most famous mode, is suffering from too much tampering of mixed ideas and no direction to them. I doubt this has anything to do with the new games coming out since this has been a problem since the earlier seasons. It really was after the buyout from Tencent that things went downhill. Every company I have ever seen go public had a quality drop. Riot Game is no different. When I watch Phreak give out his analysis or do his videos, I can see the old Riot team in him, but you can tell he is just regulated to a voice piece these days. I can feel that he wants to bring this game to better design and balance but cannot for the sake of his chinese overlords.