I’ve given this some thought and I think I can articulate why I have such a strongly negative reaction to this change.
My profile is my avatar on the Stack Exchange network. It’s the only place the community can’t edit and the only place “fluff” is allowed. Y’all are treating changes to my page and what information is displayed there like it is just about the UI and your server performance. You took away information I liked on my profile without giving me any warning or input and then essentially called me silly for caring about “vanity” stats in a place that is supposed to be all about me. The justification for some of these changes is very(very patronizingly) what you imagine is “for our own good” instead of a data driven decision that I might not like, but could accept because it’s based on something rational.
If removing “last seen” was really about privacy, you would be working to give me more control over what was shared on my profile and what wasn’t. Do you think David is proud of the Stellar Question badge earned on one of the worst scored posts on Meta? Shouldn’t he have a choice of whether that badge is showcased on his profile? If “last seen” is so creepy, why can’t I choose to hide my reviews from my activity? No-one needs to know when I’m in the queues.
Profiles are not just another page on the site that needs to be made responsive; they are personal and y’all should have more sensitivity to that. You should not be changing them arbitrarily. We should have input to the changes, and the reasons for the changes should be supported by data and facts, not someone’s opinion about whether a badge for a login streak is toxic.