This is just a way for Google to go "See! They aren't using the add-on. They are giving us consent to sell their data!"
If the domain wasn't google.com, this would look like a fairly sketchy click. At least for Firefox, this isn't a link to an add-on, rather it's a download. While I understand that no everything in addons.mozilla.org is to be trusted, I don't think it's a good idea to train people to install random things they download from weird looking random pages online.
You fundamentally misunderstand the forces at play if you think this is a failure on their part. They are incentivized financially to be user hostile. There is no magical moral compass embedded within the market that rewards those who make product decisions based on what people want, or what's good for them. They're an ads and tracking company. Approximately nobody would opt-in to their dragnet. Their whole operation is using free services as bait to track and manipulate as many aspects of human life as possible. There is no meeting where someone internally might say "hey, what do you think the user wants, what's best for them?" It's "we want the users to feel/do X, how do we get them there?"
Sadly I do understand, I just don't want to.
Would you like to open this link in your phone’s default browser or download Chrome?
Yes/Download/Ask me again every time