That's not my experience. It's a cinch to operate (with properly equipped aircraft and trained crews) but the (FAA in our case) legislation and appproval process is so onerous that we've elected to do without this approval.
Such approval is never a blanket approval; it is airfield and even approach specific. For an airline, such as Qatar, for example, operating a daily service to Kathmandu, it makes a lot of sense to obtain such an approval as the P-RNAV approach is so much easier and practical than the old VOR-DME approach. But for a global corporate operator who may (or may not) go to Kathmandu once or twice a year is it really worth it?
If your base-of-operations was at such an airfield then, sure it would make sense.
A BBJ operator which has frequent (a few times a year) ops into Seychelles decided to get approval for P-RNAV approval there (for the RNAV approach onto 13) - their aircraft required avionic upgrades, crews needed training and a consultant was hired to write the manual and steer the approval process (with the Bermuda authority). Total cost was over US $ 500,000. For a BBJ the straight in RNAV GNSS approach is not authorized, the P-RNAV gives you a DA of 410' with a visibiity required of 1,200 meters. If you don't have a P-RNAV approval and the wind is pumping from the south then the best option is the circle-to-land off the ILS 31 which has an MDA of 1,270' and requires a visibility of 4,800 meters. With the nearest practical diversion somewhere like Mombasa it makes sense (if you have it) to get such approval but is it really necessary or practical to jump through all these hoops (and conduct the specific annual crew training required) if you have no certainty of operating there?
Interesting topic - nice to have, but needs a judgment call.
As an aside (I'm stating the obvious) don't shoot a P-RNAV approach if you don't have the necessary approval as you stand a strong chance of being violated (by the local as well as your registry authority) and that'll be very unpleasant.
One day our kids will be flying these (and more complex) approaches as the norm but as it stands now you do require specific authority for each individual published approach.