We need to track lead assignment history along with qualification and classification stats in a seperate object that needs leads to be available for master-detail. This is a huge hit to our reporting and performance tracking abilities.
I agree, it would be great to be able to relate custom objects to Leads in a Master-Detail relationship. Our use case requires Pardot to send emails to Leads based on field values in the child records, and number of child records.
This would be really helpful. You can not create a lookup or master-detail relationship with Campaign Member. To replicate Campaign Member type of functionality, it would be useful to have master-detail relationship with Lead.