The ability to change the new tab page was a common target for malware, instead it is delegated to extensions like New Tab Override which are more difficult for malware to override.

Thank you, zeroknight. That explains why it is not available so far. But shouldn't Mozilla simply take the steps necessary to secure the home page option? Why is malware more likely when opening a new tab than when establishing a home page in the first place? I just don't get it.