For me: yes. A module should declare in some way the used API. If you don’t follow the trytond versioning you have to declare in some way a mapping with which trytond API (=version) you are compatible (e.g. gnuhealth modules), which is always an additional maintenance load.
At least that is the easiest way. If you are deploying from source it may be sufficient to read API compatibility via the branches of the VCS, if they are maintained in one.
If your module depends on a specific trytond version (=API), then ist should be declared.
Of course it is nice to know explicitly about supported Python versions. OTOH those classifiers tend more easily to get out of sync. More important is the declaration of the minimal required Python version in your packaging.
Could you point me to an example? I didn’t find such a classifier for django.