I can agree with this: while the reworks did add some differentiation on the basic abilities, we started with three very different champions, i.e. a Warden with team-wide damage absorption, a disruptor tank with lots of AoE knockback, and a disruptor/juggernaut hybrid, and ended up with three initiator tanks who all set up engages for their team by ulting and working from there, which in itself mirrors the likes of Amumu, Malphite, Sion, etc. Adding to this the fact that, in spite of promises to reduce tank damage, the Big Three have either had their nukes mostly unchanged, or had more added onto them (i.e. Sejuani's shatter damage), it also feels like many of these tanks are only a few number tweaks away from being divers with more CC.
With Maokai specifically, I'm disappointed that his ult got reworked completely into basically a slower Nami ult, because I think there was potential in his old one: the AoE damage reduction wasn't particularly visible, but that should have been an opportunity to amp up the effect and give it a suitably high cooldown, something Mao always lacked: if his ult were to redirect all harmful spells in an area towards himself, that would totally cement his role as an aggressive Warden (he'd very deliberately put himself in harm's way to protect his team), while giving him the flexibility he needed to either stick around the back line or advance to intercept the enemy front line. It would also add some extra skill-based gameplay to his W untargetability (untargetability is pretty much the last form of damage avoidance you'd want to give to a tank, as it means projectiles and enemies can pass through you to hit your allies), by allowing him to nullify some especially dangerous spells entirely with his dash mid-ult.
being able to nullify AAs entirely in his zone
