The default permission for FileSystem#create is the same default as for FileSystem#mkdirs, namely 0777. It would make more sense for the default to be 0666 for files and 0777 for directories. The current default leads to a lot of files being created with the executable bit that really should not be. One example is anything created with FsShell's copyToLocal.
For reference, fopen creates files with a mode of 0666 (minus whatever bits are set in the umask; usually 0022. This seems to be the standard behavior and we should follow it. This is also a regression since branch-1.