The Delay ruling irrelevant I think. I understand why it's not allowed but again it's not really one of those things you can, or even should have rules for. If a party wants to tactically organize their turn, then they will figure out a way and honestly it saves everyone a lot of headache if you just let them. If a party doesn't, then having the option to delay is meaningless. Further: not everyone is all so hopped up on a hard-fast initiative. It works well for what I'll call the "perfect game" where you have a well-behaved party, a limited number of opponents to track and everyone can make decisions quickly. As for changing spell duration, I agree that can be a problem, but it feels like such a minor issue that it's almost like you're looking for a problem.
Here's the thing: delay is such a simple ruling either A: people are going to put it in there, in which case "not including rules for it" makes WotC look like a petulant child crying out that we're playing the game wrong. or B: people are not going to use it and it wouldn't matter anyway.
I track initiative for almost every game I play in, regardless of if I DM, because I'm GOOD at it, not because I think it's important.
Their ruling on polymorph seems technically incorrect since the limitation on spellcasting is only if you can perform the requisite actions. Being a bear doesn't mean you can't cast spells. You just have to cast spells with no verbal or somatic component. A sorcerer could technically use Still and Silent spell and still cast those spells while a bear.