Purple team vs Blue team

Why does Blue team have better vision towards purple team? Why does purple team have healthier turrets? Is this supposed to dictate who we play depending on what side of the map we are on? Why not = vision, = turret hp, = chance for victory as far the map goes? I mean, its playable, but every time I play on purple team, something tells me to use a champion, that has no skill shots, because I play with screen locked over my champ(I feel better playing like this, and more importantly I am used to it) and if I am on purple team, and I happen to use Nidalee, I can't see the end of my spear shot when I am aiming directly down midlane. I see that as a disadvantage when I am using certain champs, on purple team. However, If I am using Nidalee on a blue team, and I aim my q, I can see where its going to stop, I can completely see where its going to go, but on purple team, I cannot. These are my thoughts, why not just rotate the map.