Many 3270 clients rely on Java or HLLAPI to provide standard emulation functions. The Java dependency is often time-consuming for support teams, especially considering how often Java levels change to address security issues. Furthermore, with Oracle dropping Java plugin support (January 2016 announcement), the future of 3270 Terminal Emulation solutions based on Java client applets seems compromised.
Microsoft was forced by public pressure to reinstate HLLAPI support under Windows 8 after originally announcing its discontinuation. But we think HLLAPI is clearly on its way out at Microsoft, as illustrated by the fact that Windows 10 only supports HLLAPI in degraded XP mode, which prevents HLLAPI users from accessing touchscreen and other new Windows 10 features.