"Light fares" aren't necessarily cheap.
Nobody claimed anything to the opposite. Why should they be cheap? If anything, it would make sense for them to be cheaper than the corresponding booking in classic.
2) The point of unbundling services is to maximize profits. It's not about "fairly distributing costs" between pax who use a particular service (such as checking baggage) and those who don't.
Every private enterprise wants to maximize profits. They don't care about the customer per se. Yet still, market outcomes can be desirable for both firms and consumers. So argued a guy named Adam Smith some 200+ years ago.
Why shouldn't a mix-and-match service system also be in the interest of consumers as a whole? Sure, there are some consumers which want to buy a bundle which gives them "piece of mind." (That may often be irrational, by the way.) But I think many (even some ITT) want to pay only for what they use.
Such an a-la-carte pricing model wasn't technologically feasible a few decades ago. But now it is. And, again, I think it's what many people want. Especially those who are very price sensitive and only fly when rates are low (hence the big success of the no-frills business model of the LCC.)
3) The way Light fares were introduced suggests that LH doesn't give a crap about loyalty.
To me, it doesn't. I believe even business travellers have become more price sensitive. Ultimately, I believe the airlines are cutting costs in their elite programs and elsewhere because the customer demands it. They care about loyalty programs to the extent that the customer wants them (and pays for them with his dollars).