Several comments on the questions being raised...
1. Turboprops are more efficient in their use of fuel. So, particularly at low altitude, where the endurance of the plane is key (not range), turboprops are a better choice. The P-3 can fly for about 12 hours. It was designed as an airliner, the Lockheed Electra, but adapted for Navy use long ago. Most of our P-3s are starting to wear out (fatigue)...so, we're buying the P-8.
2. P-3s can't be refueled in flight. P-8s can be, but it takes a tanker with a boom...that's USAF only...even Australia uses the NATO standard (and USN/USMC) probe/drogue.
3. The P-8s sensor suite is ideal for this search: EO, IR and a radar designed to find a periscope. Good speed to transit to the search area, good endurance on station.
4. Carrier aircraft aren't as ideal. While the carrier could be positioned on scene, eyeballs aren't always the best sensor...believe me, I've looked for a missing airplane on a couple of occasions. Even from 1,000 feet (where jets are guzzling fuel) every whitecap looks like an object of interest.
5. We don't have a carrier to spare. The preponderance of close air support sorties for our troops in Afghanistan are coming off the carriers in the Gulf. Hard to explain looking for a foreign airplane and failing to provide air support to our own troops in combat. Our carriers (we have 9 at the moment) are either on mission, training for the mission, or in overhaul. Budget cuts mean that we may lose one carrier (or even two) that is currently scheduled for overhaul, but isn't yet funded for it, increasing demand on the remaining ships.
6. Thermal layers duct the sound. It's physics...and the only way to hear the ping would be to get the sensor in the layer. But again, that sensor is very short range. We have to know where to start the short range search before that tool (which the US Navy has already sent to Perth) can be put to use.
7. This area of the world is about the most remote, hostile place on the planet for a search. I can't think of anything worse. Even the arctic would be better - no ocean to hide sinking debris, nor strong winds to scatter it. The roaring 40s (those southern latitudes) were legendary for fierce storms in the age of sail, they are still subject to fierce winds and the search area is thousands of miles from the nearest land.
8. The potential area in which this plane could have hit the water is HUGE...bigger than continents...you have to search every square meter as most of the pieces won't be very big if it hit the water. That's why satellite imagery and other methods to try and develop some focus areas...
We may never find this airplane, frankly. And if we don't, there will be no facts to support any of the possible explanations...they will simply remain suppositions...guesses at best...