The Herald change is solely because Riot refuses to listen
The bottom tower is too weak to be up against two laners. Simple as that. They could give it the buff that top and mid turrets have, but they refuse to.
Instead, they're just going to make Herald more contested with the chance it'll actually take down top before bot goes down.
Rather than fix the problem of the huge incentive there is to gank bot for the easy turret, they're opting to create the same problem for top lane in the hopes that things will even out.