Buff Nexus Towers

I don't really understand why Nexus towers are the worst towers in the game. They can barely even handle a few waves of super minions and they are the only minions that can even hit the Nexus towers. I understand the whole "Towers protect you early but you protect them late" kind of thing, but the two towers that stop the enemy team from winning the game can barely handle a few waves of super minions let alone Champions.

What if the Nexus towers had a chain beam that disabled the super minion buff and hit all minions for a flat amount of damage per tick? Maybe it does 100 true damage per second and slows champions, but does not chain from minions to champions (but will chain from champions to minions). Maybe give them a passive like 's E where they are a little more durable to quick bursts of damage but have no change vs full sieges.

Obviously those are just my ideas, but I still think the last towers should be the strongest. What do you guys think?