They weren't similar in extent to 5e products - 2e regional books would cover a much wider area, with more pages being solely dedicated to setting info. The only ones that were similar were the Waterdeep books, as both 2e and 5e cover a single city, and Chult.
The main thing is that it would be nice to break free from the northwesternmost eighth of the setting and see other regions. That's only been done with Chult so far, and it would be nice to see popular regions like Cormyr and the Dalelands start getting coverage too...