Two worlds of the same Seeds, but completely different

1.17.40 beta, * the same Seeds!

1. The world created when the world was created with the default setting
2. when the Experimental game play- Cave&Cliff was applied

Even though the above two worlds applied the same SEEDS, they become completely different worlds!!

It's not about mountains or caves.
The structure itself becomes a completely different world!

https://bugs.mojang.com/browse/MCPE-141372
You guys answered that this was intended, but do you think this makes sense?

Take a look at the screenshot that I posted and figure out what's wrong

Is this intended?
Why is it like this? Do all Bedrock users have to give up Old World?