Even if their primary concern wasn't easier, less costly maintenance for DIY owners! 
If the cost of two extra spark plugs every 10000 or so km's is a costly problem, that particular owner should perhaps go for another make of vehicle? Something like this:

I have to say, the cost of the two extra plugs does become an issue when you are charged for 4 plugs after a service. Conversation that followed:
Me: "I see four plugs on te invoice here?"
Workshop Manager: "That is correct, Sir. 4 plugs"
Me: "But this bike is a 2-cylinder!"
WM (rather condescending): "Yes Sir. It is because of the twin spark setup of the bike."
Me: "Really? This bike is a twin spark?"
WM: "Yes. All of these models are twin spark"
Me: "Why did you only replace 2 plugs at the previous service?"
WM: "Uhm ... er .... ahem ... aaah ... impossible!"
Me (rather condescending): "No Sir, this is a DL1000. It is NOT a twin spark like the DL650. How are we going to go about the refund?"
WM: "Uhm ... er ... ahem .... aaah ... hmmm ...."