It works for me when changing the 'Max Rows to print in a script' under Tools/Preferences/Database/Worksheet. Though it seems that upon SQL Developer startup, its built-in default value (5000) takes precedence. This setting takes effect only if you change its value (eg. increase it by 1) after starting SQL Developer.
When setting it to 10000, the following command gives me 10000 rows, as expected:
Software versions used:
SQL Developer version: 220.127.116.11.29
Oracle JDK: 1.8.0_31, 64bit, Linux
Instant client: x64-18.104.22.168.0 (tested with and without the instant client)