This would be covered by 0004227: "Allow users to choose any subset of supported fields in view/update/print pages."

Isn't templating kind of overkill for this request? I'd like to see a similar thing: have a configuration for the reporting form in which I can select/deselect the fields I want or need or feel to be mandatory.

Ideally, you could config this once globally as a default for all projects, and override it per project with its special needs.

BTW, if you want this feature to be per project, will templates still cover this?

it is possible to customize Reproducibility, Severity and priority for each project inserting a record in the configuration table specific for that project and all user.
just leave only one value (the default you want) for each field and user cannot change the value reporting an issue.

This is possible since 1.2 using the *_fields customization options.