A lot of the fire tvs can be rooted! There’s a great community over at XDA with all the needed resources.
I have two 4k sticks (1st gen) rooted and debloated running Leanback launcher. When you cut out all the junk, it really is (or was?) the best 4k streaming device under $50.
You can btw “simply” opt out from this in the settings (look for “featured content” and disable it).
Yes it should be opt-in, but it’s not that hard to keep the fire tv (stick) being a good device for the price paid.
You can …
For now. Until everyone gets used to it and suddenly the option to opt out disappears.
I can still throw away my fire tv stick then. At the moment it still does the job I bought it for and I won’t produce unnecessary garbage for something that might happen in the future.