I disagree MASSIVELY with your premise. What you’re saying is that scripting is always 50%-65% worth of work which is not true at all. Take the egg hunt for example. Did a lot of programming work go into it? Sure! But the amount of programming work probably did not match up even close to the amount of building that had to go into it. This brings me to the first point: Work Done. Whoever is doing the most work should reap the most rewards. You can’t simply throw out an evaluation and say that applies to ALL PROJECTS. Building can sometimes be intensive, and so can graphics and so can music. It all depends on the project.
The next point Id like to say is that you say scripting is continuous. There are always bugs you need to fix and other things. I agree. Scripting requires your constant attention. What I do want to say is that other people need to do things continuously too. Builders need to update with new maps and new things to explore to keep players interested and happy. A large majority of the time new graphics and new icons are constantly needed too. This is important to consider.
The last thing which I find the most important is RISK. If a programmer is getting paid 10k USD to make a game, should they really be getting the most percentage. In my opinion, it does matter how much work is done but it is all relative to risk. If the person is putting nothing on the line by doing the project, should they really be receiving a percentage of it and getting paid from that? It doesn’t make much sense if there’s no risk involved for the programmer and any other members who are paid to reap the rewards of a project. If the programmer and other members are involved in risk, I definitely believe there should be a percentage involved and depending on how much risk is engaged that percentage should be changed. This stands true for a lot of projects on front page today and continues to be true for anything.
I would recommend any person, builder, programmer, or graphics artists to assess these things when deciding how much they need to be paid to call it fair. Programmers do a lot of work and the majority of the time it is a large portion of a project, but you should assess these things when thinking about joining projects or getting paid via one time payouts.
Hope this helps not only for programmers but any person that needs to assess their worth in a project.