Help yourself: compatible 3D printer parts that are easier to swap!

Why would I ever re-design a working part of a printer?

It does look robust, but hard to disassemble! (Escher)

Most of customers and users do not tinker with their 3D printer. After all they paid for a robust printer and spent a lot of time setting it up properly. Once done, it stays so (well, at least with the Ultimaker). Sure, it is a desirable feature, especially for the "boxed/walled" frames. But it may get really annoying when you are trying printer part alternatives in the first place, which is the subject of this post.

By the way: there are really two main usages for a 3D printer: the obvious first is to print objects... while the second is to print replacement parts for the printer itself! Sounds weird, eh? "So what are you printing with your amazing printer? - Well, most of my time-consuming designs are printer part replacements!"...

Now back to the question: why shall I sometimes just re-design a part of the printer with no added value beyond the ease of manipulation?