Why has teleport been nerfed into the ground?

First off you can't cancel a teleport anymore

Second the cooldown is 6 minutes, which is a joke considering ignite is 210 seconds. I ignite you in a trade and you get away. You back, and you return with teleport. Now my ignite is back up and I can try to kill you again and if you die or not you can't teleport back to lane because, oh wait, it's on cooldown.

Third: I play a lot of nasus and I don't even take teleport on nasus as ignite is quite literally that much more superior to teleport.

most games are at most 30 minutes, that's 4 teleports a game as you can't benefit from teleport at the beginning of the game. Now we also take away the fact that while you have teleport the cooldown of your next teleport is still remaining at 360 seconds/6m. So in the average game teleport will result in 2-3 teleports. Take this vs something like exhaust or ignite and every 3.5 minutes you can ignite your enemy for poke, extra damage, securing a kill, reducing healing, etc. I play a lot of lane s and I often find myself using ignite to just do extra damage to the enemy just to proc the early cooldown + give me kill pressure or just push the guy out of lane. Since he has teleport he's gonna need to burn teleport when we trade because he'll be so low on health I can kill him but luckily he has tp but I have ignite in 120 seconds, or 2 minutes. Now I have 3 ignites to his 1 teleport back which he couldn't take advantage of because of such early back timing. See my point?

Buffs that did this for tp and ignite: +ignite dmg +ignite dmg -30 ignite cooldown, +60 teleport cooldown -teleport cancelation ability.