As a customer I would definitely want the recognition. Commercially, I don't think it makes that much sense but it all depends on the population profile. Take you as an example, you are lifetime gold with QF but when was the last time you were onboard. I would relax and not worry about renewing my status YoY (not that 50K is much) and might focus my attention on other airlines.
Having said that, another way of looking at it is I would strive to retain status for the next x number of years to guarantee myself lifetime and this is guaranteed revenue for the airline.
I have actually been flying QF a bit lately - given that I am in Australia monthly, so my lifetime status is useful because I don't fly enough with QF to maintain any type of status typically.
With both QF and UA, when you earn lifetime status, you only receive "mid-tier" recognition (ie Gold for QF and Premier Gold for UA) so its not as if they are creating another level.
It's not to say that if you earned 1M tier miles with EK, I would be happy with Lifetime Silver though....
