tipical use case for the Service Portal is to manage request regarding creation of multiple mailbox, accounts and so on. For instace, the IT manager is onboarding 8 new consultants and he makes a request of a userId and/or a mailbox for each consultant.
For each consultant, he has to provide detailed information, like name, company, business email, an so on..
Based on the current capabilities, the requestor should submit one request for each consultant (one user option for each attribute, one Request for each consultant) or to provide the expected information in a attachment (like xls template).
Both proposals are often not satisfactory for the customers, the expectation is to have one of the following options::
1) a dinamic set of fields
2) a grid with a variable number of lines where the requestor can fill the cells.
The first option is currently achievable in someway with a predifined number of user options (lfor instance, if you want to manage 5 attributes for each consultant and a max number of 10 consultants, you have to create 50 User Options) and some business logic to manage the user option visibility but the effort is high and the result is poor for the user experience.
I have customers with Service Catalogue plenty of this kind of offering.