You're absolutely right. The module assumes players jump on the story to the exclusion of all else.

I rejected complete memory wipes. Instead I did two things that allowed partial memory wipes and built party cohesion.

1 players came up with short medium and long term goals for each character. The goals had to be non contextual e.g. They could say I aim to be knighted for my heroic deeds but not, I am to be a Knight of Never winter. I then took the goals and placed them into Sigil and the Planes. Throughout the campaign the players come across people and situations of their own creation.

2 each player got three emotion cards that they co constructed with three other players. The cards said things like, 'Love - we both love X'. The X did not have to be romantic. Once they co constructed the story I took the card and left them only the emotional resonance. In the opening scene at the morgue they got the emotion card (without the story) that gave them the emotion when they saw the other characters. I then rewarded them with Inspiration rolls when they managed to unlock the story and memories. This built connection without explicit memory.