I've encountered a few pieces of math that are more naturally expressed in 0-based indexes and it is pretty easy to define them in Julia using arbitrary indexing.
TaylorSeries.jl is a great example of this. x = x_0 + x_1 t + ... Then indexing into it with x[0] would give the zero-th order Taylor coefficient.
The opposite would be true for a large swath of people coming from scientific computing backgrounds if Julia defaulted to 0-based indexes. That said, in my experience people doing scientific computing have a poorly calibrated sense of what constitutes “hard.” I’m sure plenty of breakthroughs born of brilliant and horrifying code were created over sleepless weekends by grad students who didn’t understand that what they wanted to do was a mental tax.
I guess I don’t hear a lot of people doing scientific computing complain about indexing schemes. I prefer 1-based indexes, but 0-based indexes is a small and trivial issue in my list of grievances against, say, Python.