There is an immense value in most of the ecosystem converging on Python over the last decade and especially with leaving MATLAB behind in the dust. I don't think decade long transitions from old tech to new tech is a bad time scale or even close to that of the churn of web technologies. Julia offers enough of an improvement over Python to warrant a switch over the next 5-10 years and leave Python behind in the same way. I believe Julia offers the same level of improvement over Python as Python does over MATLAB.
I also believe that it has drawn too much from MATLAB only for the sake of being familiar to that group and not the computer science and software engineering communities though such as the one based indexing you mentioned. Unfortunately that ship has already sailed and we will likely have to wait another 10 years for the next one to hopefully fix those problems.
Back 5.5 years ago, I used to complain about the 1 based indexing and the column-major structure of matrices in Julia (both like Fortran), however, those issues have been solved by OffsetArrays and PermutedDimsArrays, giving far more flexibility that is possible in most other languages.
It's silly to keep bringing up the issue of one based indexing, when you can use any integer as the base, just like Fortran 90 (so you can index by -5..5, for example).
For some things, 0 based does make things easier, sure, but you can do that easily in Julia (and more!)
Yes it is possible to make those changes and even if it wasn't it does not detract from the impressive and useful innovations Julia has made. That is why I usually refer to them as cosmetic but that is possibly not the correct word either because it does not convey the implications of having that default beyond simply being unattractive. Cultural may be the correct term.
Julia claims that it wants to solve the two language problem. To do that it must win both the scientific compute, HPC, data science, machine learning, etc. group and the CS, software engineering, dev ops group. I've shown Julia to quite a few members of the latter and they always love the idea and technical capabilities of Julia but visibly cringe when they find out it uses one based indexing. They also almost universally find the syntax ugly.
Unfortunately the available packages to change that also does not help because most people will never change the defaults and IMHO it would be bad to do so. When writing Python you follow the PEP-8 style guide, it is just best practice to follow the languages conventions so everyone is on the same page. This is the same problem with C++ trying to add all these new features and a solid package manager like Rust has, it will never fly, people just won't use it everywhere, it isn't going to be in the standard library, It isn't the default and it isn't part of the culture.
I also believe that it has drawn too much from MATLAB only for the sake of being familiar to that group and not the computer science and software engineering communities though such as the one based indexing you mentioned. Unfortunately that ship has already sailed and we will likely have to wait another 10 years for the next one to hopefully fix those problems.