See here: failure to reveal a morph at the end of the game is no longer a Game Loss at Competitive.

The article goes into a bunch of details as to why, but basically it comes down to three things:

1. It happens a lot. Or at least often enough that it keeps coming up practically every tournament. Which is annoying.
2. Cheating with morphs is an incredibly high-risk ploy for a gain that's mediocre at best. Which means it just doesn't happen.
3. The Game Loss penalty incentivized players to keep quiet in the hopes of "Gotcha!"-ing their opponents to get free wins, in some cases going so far as to try to deliberately distract or mislead them into failing to reveal. Which is downright terrible.

So they took a hard look at the penalty and the underlying philosophy and decided to shift the implementation around a bit so that the relevant upgrade no longer applied, since simply being at the end of the game (or casting a bounce spell on something) gives the opponent the chance to ask what your morphs are.

Note it's still a Game Loss if you actually misplay a non-morph as a morph; there's some wiggle room if you catch yourself immediately, but not much.

Finally. This was one of the dumber rules and I was surprised they didn't change them upon release, almost like what they did with the Legend rules again.

Eh, the rule itself is perfectly logical--nobody wants Merchant Scroll to be a possible Demonic Tutor. A number of factors just happened to combine just so to make things go all pear-shaped. The lower possible gain, the sky-high risk, the likelihood of innocent mistakes, the potential for gain in silence--it all just made for one big mess.

I'm not surprised about the delay--morph's been around multiple times before without issue, after all. Why would they have thought it'd cause problems now when it didn't then?

I think this all highlights the problem with morph as a mechanic in the scope of tournament play more than anything. It's a game mechanic in which you are actively able to cheat or lie about what is happening and it puts all of the burden on the opponent on catching it after a game as ended. The rules surrounding morph make sense, but the mechanic itself is terrible.

Morph caused this same kinds of issues during Onslaught because morph was everywhere, but in Time Spiral morph was on a few cards and wasn't really a core mechanic of the game play. I also think we've moved away from rules that punish players for not remembering something or something you can't really gain an advantage from. For example, sideboarding too many cards used to be an offense that punished people for not counting their deck when they already didn't gain anything by having an extra card in their deck. To be fair, you should have to keep your own board in check at all times but downgrading morph to a warning makes sense to me.

Downside of this is that there are people who do cheat. Somebody actively faked morphs/equipped ghost blades in a PTQ against one of my friends.

if you're worried, I assume you can ask still them to reveal. the game rules still say they have to, this is just a change in the penalty.

Yeah, they still have to reveal; if someone's consistently not revealing (or even just doing it twice in the same day) then it's going to look very suspicious.