Even though Inbox by Gmail has always been a testing ground for Google's main email client, many users now prefer it — myself included. It was already dismaying to see the removal of certain snooze options (place and someday) in June, but now it looks like the 'Save to Inbox' sharing option on Android has been axed as well.
Now, when you tap the Inbox icon in the Android sharing menu, you get taken straight to an email with the link ready to send. You can still send it to yourself and then add it to your 'Saved' bundle, but it's a lot more long-winded when you probably just need a quick way of preserving something for later. If you copy a link manually and then head to Inbox, the link saving floating action button (FAB) is still there (see image below), but pressing it again takes you to an email with your link imported.
Either through the FAB or sharing menu, I still end up with just an email.
It's unclear why Google has removed 'Save to Inbox' on Android — perhaps it thinks the functionality isn't very popular, or that it confuses some users. For the time being, it's still possible on desktop via the Inbox Chrome extension, and the FAB method works there as well. There's no telling whether Google will also remove those options in the near future.
Gmail's recent redesign came with a couple of features from Inbox, snoozing included, but we still expected Inbox to keep going strong. That seems less certain now with more features being taken away than new ones being added. If I may address you directly: Please don't do this, Google — I'm not ready to go back to Gmail just yet.