If a module does not provide a formatter named 'default', initially no formatter is being used, making fields invisible.

This is a problem if a module provides two or more CCK fields, which require different formatters (eg. my module has an image field and a text field).

Possible solution would be to add a HTML select for the formatter in the field editor. This way, the first possible value would be selected even though a 'default' formatter wouldn't exist.

Other possible solutions include allowing field-specific default formatters, or allowing the field to set its formatter when being created in eg. hook_field_settings.