In choreography, I do think there is value in weaving together many different technical elements. Choreographers take into account what jumps the skater can do, they try to match the placement of the jumps to the musical structure, etc.
There are some PCS areas in which variety of jumps attempted can have an effect. E.g., a skater who does a lutz or two is likely to include more multidirectional skating than one who does none; a skater who does loops and salchows is more likely to have more curved approaches whereas flips and toe loops are more likely to be approached straight down the middle of the ice.
But even those qualities aren't guaranteed, and they probably would not be worth even a whole 0.25 worth unless "variety of jump approaches" were written into the (Choreography?) criteria and written guidelines instructed judges to emphasize this criterion.
Let's say we agree that variety of skills is a good thing. Should that be written into the Choreography criteria the same way Variety for transitions is written into the Transitions criteria?
If there are particular skills that we feel must be demonstrated in long programs, they would need to be written into the requirements. That already includes an axel-type jump, a combination spin, a flying spin, a spin in one position, with limits on repeated spin features.
Would we want the free program rules to require one of each of the basic jump takeoffs (number of revolutions unspecified), such that the last jump element or two would get no credit if they repeated takeoffs already performed while other takeoffs had not yet been attempted? That would heavily incentivize skaters to attempt all takeoffs -- but if they know they can't rotate the triples they'd be better off trying doubles. And it would make the free program even less free than it already is under IJS.
Variety of basic skating skills is covered in the step sequence rules -- a certain number of different kinds is required for level 2, more for level 3, more for level 4 -- and using more varied methods of changing direction and more of the difficult turns would contribute to the Multidirectional Skating and One-Foot Skating criteria of Skating Skills, and the Variety of Transitions.
But if it were important enough to build in heavy rewards for including a triple lutz (not even a good double lutz or last-second flutz would meet that requirement?), then wouldn't it also be important to make it equally mandatory to include, say, at least one clean counter turn somewhere in the program?
Certainly it makes more sense to expect all senior-level skaters to demonstrate the ability to do counter turns (a difficult technical skill based on pure skating technique) than to expect all senior skaters to do triple lutzes (a difficult technical/athletic skill based on body size, shape, and muscle fiber composition as well as technique).
I don't know that any changes in the actual rules are necessary. I look at it like this. Suppose you are a parent. You send your child for skating lessons. He learns this skill and that. He learns how to do a toe loop, then a Salchow. Eventually he reaches a level where he can enter a competition, aka recital, where he demonstrates the skills that he has learned.
Many tens of thousands of dollars later he gets to the top of the heap. He has learned all six jumps, plus upright, camel and sit spin variations and cool moves in the field. For a few thousand more you hire a choreographer to string these element together in an esthetically pleasing way, to create a mood, tell a story, and express the character of the music.
To me, a young lady who presents, say, two triple Lutzes, two triple flips, two double Axels and a triple toe -- well, that will rack up a lot of points on the TES side. But the recital is incomplete even so. I want a refund form the coach -- he was supposed to teach the loop and Salchow as well.
The ISU doesn't require tests to enter international competitions. Federations can send whoever they want, who meet the age limits.
There are required elements in the short program. So if something should be expected of all senior competitors, require it in the short program. (Or make long programs even more about requirements -- i.e., even less of a "free" skate.)
If it's just to be rewarded, then build in rewards, but recognize that skaters will be free to skip a particular skill that gives them trouble and build their scores with other skills.
If there's a high-value skill that most of the top skaters can execute, then anyone who doesn't have that skill will be at a disadvantage. But she can compensate for that lack by excelling in other areas. That goes for specific jumps and also for specific turns.