In short, the fact that Cocoon is just a bunch of parts that get configured is one of Cocoon's major strengths. However, the current configuration is pretty easy to understand and modify. If the replacement container makes the configuration more complex and less understandable that will really hurt the acceptance of the product.
TBH I always thought that DI moves some complexity from Java code to configuration. But I think that there is an overall gain in simplicity and transparence. If I look at Butterfly's applicationContext.xml it's quite straight forward IMHO.
Guido