1). I love playing support, as do many others. I love that I don't have to worry about CS at all, just poking and laning. I love that I am not responsible for carrying the game, I am responsible for carrying the people that carry the game. I love everything about the roll.
2). Maybe in extremely low elo that is an issue, but even in silver nearly every game has a support for both teams. Sometimes off meta, but still a support.
3). If ADCs didn't have a support and it was a "1v1" it would be a 2v1 with the jungler hanging out with you all game. ADCs (attack damage carry) need to be protected as they carry your team mid to late game. Arguably even earlier. But they are not invincible. And bot lane is a long lane, meaning any kind of meaningful gank on just an ADC in the middle of the lane would result in your death.
4). They are by no means a waste of space. If it was more efficient to not take a support and instead have double ADC bot lane or something, people would do it. People play what wins. I play Ardent supports as they provide your team with sustain like no other roll can provide. Supports quietly do more than alot of laners. There's just no way to measure how well they are doing it. Altho I will admit Riot is doing better at gauging that by keeping track of healing and shielding done to allies and vision score.
Not to mention, if you take out the support roll, there are about 1/5 of the champions who no longer have any purpose, or have no purpose in the proposed gamemode.