I’m in total agreement — though not in a position to do anything about it but complain.
As an active user on Stack Overflow, I found the little blue number indicating changes in responses, reputation, etc. to be the single most important piece of information on my profile page. I could look at my profile throughout the day and see if anyone responded to my comments or if an answer was accepted.
In short, it enables us to be responsive over a number of posts without having to monitor each post manually. I think it’s an important feature that needs to be reimplemented.
Nick Carver commented on this answer:
This was a styling issue more than anything else, we're now
constrained space-wise horizontally with the tabs. The indicators are
being worked on right now, I'm converting mobile to use the new code
and Dalgas is working on indicators, you should see them return soon.
At least we now know the indicators are coming back. This is good news.