I feel that the parts editor needs to be finished so we can stop working with XML files and doing everything manually and instead do it all in the editor. It seems that a lot of what you want is the result of your trying to make things as strict as they had to be before the editor was built. It also appears that the editors purpose it to make parts creation easier by allowing things to be assigned however they are and not have to have everything perfect as you would like. I personally like that you can do things how you want and that you do not have to follow strict guidelines to get a working part.
I personally do not like forced standards as they stifle innovation. If no one had gone against convention we would still be using a rock as our most advanced tool. Allowing people to work the way they are comfortable lets them be the most innovative.
When I make parts I make an SVG of the part with the copper in copper groups and and a silkscreen group, that is all. All other assignment is done in the editor. It takes no time and you never get it wrong. Sure things might look ugly in the XML but if you never look at it who cares what it looks like. 300 groups deep, who cares it still works and I never have to deal with it. It only takes a couple of minutes to make an SVG if you don’t have to worry about making terminals or assigning names to each pad/ring etc. Then it takes only a few seconds to assign the rest with the editor. To make a part completely via SVG and XML it takes much longer and if you have started from an existing part you are likely to have errors. If you start the SVG from scratch it never has strange extra transforms etc. I haven’t had errors making parts since I stopped trying to edit existing parts and started drawing new SVGs. I also keep the original SVGs I create for editing later so I never have to open the Fritzing modified SVGs.
Do note that none of what I have said is in regards to the breadboard as I do not use it and wish it could be turned off when not used to speed up loading and to reduce the risk of errors as it only seems to be possible to corrupt a sketch when using the breadboard and making changes in the other views. If you never work in the breadboard you can make changes between views repeatedly without causing the mysterious extra ratsnests bug.
I know that all of my parts create perfect PCBs and readable schematics. I also know that my parts would fail most if not all of your scripts tests. Does that mean my parts are no good? No. They are all perfect (for me) and work exactly as designed. If you run the part I uploaded MCP1700-xx, SOT-89 through your script you will likely see what I mean. With that all said I think people would rather have as many parts available to them as possible even if they are a little buggy if the other option is nothing making it into core parts because of strict standards. Obviously incorrect foot prints and similar issues that prevent them from being used need to be fixed.
All of the above is my personal opinion and is not intended to make your opinion any less valuable.