For the record, I have never taken off the auto-tips. That said:
In an earlier life, I worked as a Payroll Accountant in the Shipping Industry and therefore appreciate how valuable the tips are to crew. They are very heavily dependent upon them.
The NCL comments re-low staffing levels I have heard before and I know this has resulted in people reducing the tips. Simple solution do not sail with NCL.
A more honest approach IMHO would be to consolidate the tips in the cruise fare - but I can hear the objections already!
BTW my brother, whilst on a business trip in NC, received appalling service in a restaurant - paid the bill but left no tip. The staff accosted him physically outside the restaurant for leaving no tip! He explained why and they retorted that the level of service received should not influence tip left. That does not wash with Europeans!
Pay the staff a reasonable rate of pay and tipping would not be so contentious! The staff would not be so heavily dependent upon them.