I felt the same way at first but I've gotten used to the "7.1 way".
Using the search box works for me. Set the date range and type the custom severity in the search box to filter the result set.
If I have multiple custom severity tags, I use the same first few letters or company abbreviation i.e. ABC_Critical, ABC_OfficeApp, etc. That way, if I want to see all of them, I type ABC in the search box. If I only want one of them, I type in the whole name of the custom severity.