Plus, phase 1-3 teases always clearly showed the main draw of any new characters they revealed in the post credits. Nick Fury is a government guy putting together a team of superheroes. Cool, sign me up for some of that superhero teamup action. Thanos is an alien mastermind behind the Chitauri invasion who is manipulating events from afar. Cool, I wanna see what this guy is planning next. Hydra used Loki's staff to experiment on a bunch of people and the only two survivors are a pair of twins with super speed and telekinesis. Cool, let's see what they can do.
Whereas I literally have no idea why Thanos suddenly has a brother (who looks and acts nothing like him) or why I should care. I have no idea who purple sword lady is or what she has to do with anything. When BW came out I had no idea who Val was and why she was lying about Hawkeye (actually I'm still not sure what her deal is). And while I'm familiar with Hercules from Greek myth, as far as the MCU goes I have no idea what kind of story he would be involved in or why I should care. Heck, even with Beast, even though I'm excited to see the character, I still have no idea what will happen with him.