Small LO_BUFSIZE slows down lo_import and lo_export in libpq

In libpq, in the code of the lo_import function, for each piece of a file
of 8KB in size, lo_write is called, which greatly slows down the work of
lo_import because lo_write sends a request and waits for a response. The
size of 8KB is specified in define LO_BUFSIZE which changed from 1KB to 8KB
24 years ago.
Why not increase the buffer size?