I've just spent 3 weeks on Cocos-Keeling Islands and I was stunned at the absolutely vast amounts of flotsam and jetsam littering the shores of the islands.
I was always under the impression (now sadly corrected) that the Indian Ocean was one of the worlds cleanest oceans, and I was very pleased to live on the Eastern edge of it, and revel in its cleanliness.
The truth is, the Indian Ocean is a watery garbage pit, on a par with every other world ocean.
Much of the flotsam and jetsam has Asian origins, and much of it is reputed to be remnants of the Aceh and Fukushima tsunamis.
I believe a lot of it is even more recent and is a result of purely a lazy disposal attitude, on a large percentage of the population of the above nations.
Surviving MH370 wreckage (and there is bound to be some) would be buried in the overwhelming volume of general rubbish that populates the Indian Ocean.
AFAIC, the greatest failure on the authorities part is not immediately issuing a reward notice to the populace of every nation and every island and continent bordering the Indian Ocean, for a monetary reward for any possible aviation-related flotsam or jetsam found in these areas.
Even just one small wreckage item from MH370 would add to the tiny levels of available information and enable researchers to try and calculate the track of the wreckage.