If memory serves, Apple did precisely this with FileVault for a very long time. Google did the same thing with encryption on phones. It was all quite thoroughly optional and all the warnings were thoroughly clear.
People can, will, do, and did ignore any and all warning messages and then look to support to help them. It does not seem to matter how large, scary, or clear the warnings are. They will be ignored.
So if you're Google or Apple and want to ensure that people's identity documents or tax records or business documents aren't stolen when the laptop or phone is, you make encryption the default. It helps that these devices are easier to sell to businesses. I'm thankful for these choices.
In my professional capacity as an information security practitioner and my personal capacity as a privacy advocate, I find the idea at hand distasteful. Improved security should be available to everyone, not just those with a deep grasp of how to manage cryptographic keys. Gaining any measure of data security should not be reserved solely for us in the technical elite.
There might, perhaps, be a slightly different discussion to be had about making it more common for tools to enable advanced users to manage their own keys. But this should never come at the expense of the common user. We have a profound professional responsibility to be better than that.