Originally Posted by brunos

Sorry, planestupid, I did not mean to offend you nor was the comment directed to you. It is just that this topic has been discussed so often on FT and often you get posters stating that "it is obvious that.." or "it is just like...". The reality is that the passenger agrees to a commercial contract and the contract explicitly states that all segments must be flown and in the order issued. One can argue that it is silly, one can try to make some comparisons with other situations (which is irrlevant IMO). But the case remains that by dropping the last leg of a ticket, the customer is violating a previous agreement.
I agree with you that an airline will not sue a pax, but they have other means to enforce their contract as discussed above. Hence it is usually the pax that sues the airline to recover their money or ticket. Unfortunately for Germany the High Court has de facto ruled in favor of LH allowing it to reprice a ticket if a violation is found.
Whether someone finds the rule illogical or stupid is another issue. But such rules are consistent with the way legacy airlines impose geographic-segmented pricing. If one does not like it, he/she has the option of LCCs.