For inspections, you might want to take a different approach and instead configure your inspection templates to Require Asset on Close. Inspections are generally going to need to be attached to an asset anyway, and then they will get the X/Y of that asset. It's not perfect since inspectors may never close the inspection.

Service requests are trickier since there are many situations where a service request legitimately has no specific location. These may not apply to your organization, but things like anonymous complaints about general service levels, requests for 'virtual' services, etc. are examples where there is no location.

You can make X/Y required fields but I don't think it's possible to force them to be required on creation, only when they're being updated later.

Generally I think making X/Y required can cause problems as users are forced to geolocate activities when they may not have or know the correct location. A different way to approach it is to set up proactive monitoring with a report showing all the activities that are not geocoded and following up as needed.

Field Validation might give you a way to display a warning message if the activity isn't geocoded - I don't recall how it worked in version 15.