They're not that sparse, surprisingly (or, is it?). Especially if you take E and U fares into account. These four many times are the only ones LH offers on their web-site next to Y fares when you're trying to book an eco-ticket. And they're not necessarily cheap and hardly ever flexible, but they all certainly only give you 125 miles. Go figure!
From a miles perception, flying LH in coach within Germany or within Europa isn't interesting at all. The only reason to use them is if their fares are cheap or you can use the perks you have earned on the longhoul like lounge access, etc.