A cost vs. maintenance perspective should be part of the equation. The industry strongly recommends annual servicing. The 'average' diver does how many dives/year....6-30? It's pretty hard to get a solid statistic.
OTOH, it's been pretty well shown that a decent reg, well taken care of can go for a lot of dives and often go years before needing an overhaul. Most divers simply do not need an annual overhaul, especially the occasional tropical vacation only divers. Divers that actually do a lot of dives, know who they are and likely pay attention to their regs.You go a few years NOT doing an annual, you void your warranty, but you save so much money that the [parts for life program] is useless. My wife and I both threw in that towel a decade ago.
The industry doesn't want to support that kind of thinking. Part of that may be liability, and part of it is simply profit. Fear is a great motivator.