Yes, really. You are looking at it after the fact. Paying off a pilot who is skilled enough to fly the aircraft evading all radar and land it unassisted at night or early dawn on some remote airbase would be a major expense. Paying someone to kill off the rest of the 220 passengers would be a big challenge as well. And everybody involved would know that and the additional risk and thus demand much more money. You would have to find such an airbase. And you would have people at the airbase to take care of everything, including hiding the jet from satellites. And the airbase would have to be unused and remote. Ditching the aircraft safely into calm waters is even more unrealistic. First of all AFAIK it has never been successfully done with a wide-body aircraft and even in a small-body aircraft it would be a major risk. It would require perfect weather and calm ocean. And it would have happened at night!
There are a ton of risks involved in all of this. How could they hijackers have known that the Malaysian air force wasn't properly looking at its radar? They could have scrambled jets at that point and all of this complicated plan would have been for nothing. What if the flight they allegedly used for the radar shadow would have been delayed or they would have been delayed? What if there had been a military ship with their own radar on an exercise or patrol? After all they flew over one of the busiest water lanes in the world with an active piracy problem. What if ...
You are looking at it after the fact and not from the perspective of someone who had to come up with the plan and evaluate all the risks.
I'm not saying that kidnapping or killing a handful of people on the ground would be easy. But compared to such an unprecedented and skilled aircraft hijacking plan it seems like a piece of cake. Not to forget all the attention that MH370 gets.