You seem to have an incorrect understanding what end to end encryption is used for.
The only guarantee of end to end encryption mechanisms is that the sensitive information is secure whilst in transit. There is no guarantee whatsoever that the receiver will do the right thing to safeguard that sensitive information after it is received.
Let's imagine a scenario where a host asks you to send your passport photo via WhatsApp, and you do it because you know WhatsApp uses end to end encryption and you think that, as you said, "it is OK". What you didn't know is that this host prefers to save all passport photos they receive via WhatsApp to their laptop. So you send a photo of your passport and they use WhatsApp Web on their browser to save it to their laptop. You go and stay at their property, everything is fine, you have a lovely time, you return home. A few months later the host's laptop is stolen. Now the thief has access to your passport photo, not to mention the passport photos of all the other guests who stayed with this host.
As you can see, it didn't matter at all that you used WhatsApp, believing that it was safe to do so because it has end to end encryption. The host failed to keep your sensitive information safe and now it's in the hands of a thief. I don't know about you but I sure would lose sleep over this.
Just because a system uses some form of end to end encryption mechanism doesn't mean that your sensitive data is safe no matter what.