As NI starts pushing 64-bit LabVIEW more (and deprecating 32-bit), I think it would make sense for NI to start moving things like this to using the I64 instead of the I32, including array and string functions. I'm actually struggling to quickly find other examples of things that use I32. VISA Read uses a U32 for the byte count; Set File Position is a U64. But I'm sure there are a ton of VIs NI would have to update to do this, so it might be more effort than it's worth.
All the array data types are limited to I32 length values. All the array indexing and similar use I32. Changing any of these has huge and very difficult to oversee consequences and changing it partly would be an even worse thing.
With a LabVIEW team as 10 to 15 years ago, it may be a doable change request, although it would be a major project in itself. In the current situation it's nothing less than impossible.