The midlane turret could be walked to, and literally made several champions ultimates useless early game (Karthus loves his opponents moving 2 feet and shielding his entire ultimate everytime early and mid game). It needed a nerf. The personal shield was nerfed because unless you could autoattack a turret 2-5 times (depending on if you were an adc/nasus or a support) they kept the shield throughout any siege, and if you COULD autoattack the turret 2-5 times you already won the siege and got the turret. The personal shield being weak means if someone can successfully get to and attack the turret they can weaken the defensive strength it provides for a while.
Also, seriously? The laser turrets literally outdamage every other turret on the map and do more damage then the old base turrets ever did. They have stacking armor pen (up to 75%) and massive damage. For math, laser turrets max out at 290 AD (~43:00 minutes when they max) compared to 250 for the inner turrets, 4.0 AS compared to .83, and 75% armor pen compared to 30%. Their stacking counter is weaker than other turrets (ramping up to 125% after 5 seconds compared to ramping up to 225% after 4.82 seconds), but when taken with their AD and per hit their damage is MUCh higher. A max heat laser turret does 2610 damage a second; a max heat inner turret does 674.38.
So no, laser turrets are still MASSIVELY powerful (2610 damage a second? That's adc levels of damage, and comes with 75% armor penetration); people just don't realize it because A) their damage comes in literal DPS with no spikes or jumps and B) at the point in the game where you are against laser turrets most people are full build/close to full and can ignore the laser until it has ramped up enough.
