These fields cant be marked as required in Default Field Configuration. But without them creating issue from Crucible doesnt make sense because then I need to open JIRA backlog and edit this issue... What is workaround of it?
The only workaround is to create the issue directly in Jira. However, the following applies:
If any required field for the selected issue type is not supported, Crucible displays an error, with a link to create the issue directly in JIRA Software. This link will pre-populate the project, issue type, summary and description fields, but will not create a link from the comment to the issue.
Can you share which method/link/user interface option exactly are you using to create the issue?