Hotel Tango. Yes, I agree and wish it were not so. If you are a single pax, or low tier, you get a standard letter and the complaint gets added to a pile and, I dare say, is reviewed with others at years end. If you are high tier, or corporate, you get a few more FFMs.
The problem is not just the airlines. I cannot think of ANY company to whom I have complained that has not brought the standard letter but, mostly, silence. I have tried old style letters, emails and phone calls but NOTHING happens. If you get a standard letter, consider yourself lucky. I do not have the time to waste.
We have all sat listening to the, "Your phone call is very important to us" when the system is designed to keep people waiting the maximum amount of time so as to reduce costs. (I was in telecommunications for 27 years)
Western people have demonstrated that they want the lowest price possible - and we have it! I first noted corporate customer service failing in the USA in the early 1990s.