Two questions about combo ports.

I have been quite struggling to understand some things about combo ports and didn't find the information I needed on google so I thought I'll leave my two questions about combo ports here.

1.Why would I ever want to use 2 physical interfaces acting like 1 logical interface instead of 2 physical interfaces acting like 2 logical ones?

2.In what kind of situations it is better to use combo ports instead of regular ports?

Thanks.