I haven't read the whole thread (and I never was a JW) so apologies if this has been mentioned.
Apart from the obvious (power, ego, 'big fish in a little pond') I can't see any reason why anyone would consent to serve in a position of responsibility.
They may have liability in child abuse cases, of course, as has so well been demonstrated recently. And the 'Menlo Park' fiasco. But I'm fairly sure that as access to information continues to increase exponentially there will be other liabilities. One that springs to mind is 'Data Protection' legislation and its equivalents in various countries. KHs keep vast amounts of personal information, and the keeping and use of this is regulated. Plenty of opportunities for civil and criminal liability.
I think I've read on various posts that WTBTS in its various guises is distancing itself from local congregations - in that local congregations are to be seen as separate legal entities from WTBTS itself. That could lead to personal liability for elders/trustees. (This is a complicated legal issue and varies by jurisdiction, but the concept of 'personal liability' seems to be increasing in most jurisdictions).
Even if I WAS a JW, and 'qualified' I would be very, very, wary.