I understand your frustrations with WiX its sits over a very complex installation suite. (Windows Installer). I also understand NSIS essentially makes development life easier but it certain doesnt add anything to management.

Windows Installer is however a complex installation suite which maintains so many more advantages over something like NSIS. You can benefits such as
1) true transactional installation
2) self repair
3) application sociability
4) user impersonation
5) managed installation
6) rollback
7) upgrade
8 ) custom action extensibility
9) open installation framework
10) enterprise deployment

the list goes on and on, none of which NSIS supports.
NSIS is great do deploy a single application
Windows Installer is designed to manage an entire installation framework for an infinate number of applications on an indefinate number of platforms. It caters for locked down user deployment, designed to work with most deployment technologies such as SMS, Altiris, Managesoft to name but a few.

You made the right choice with windows installer, i think if you find the right person to train your team you will find it considerably more useable.

WiX is simply a declarative language to generate Windows Installer apps and I personally think it does a great job of doing that. Its no simple tasks to manage such a complex framework.

I hope you have sorted out your issues and not turned to the dark side.