Right now, you can link an already created idea at the Salesforce account level, but you can create a new idea. This has been requested from many of our solution architects supporting current customers. Would be a big help in encouraging additional idea creation with current customers.
You can already create new ideas through the Salesforce integration on the account screen in Salesforce. If you are seeing a problem with that process please open a support ticket at firstname.lastname@example.org.