Let me try to answer this. It will be both easy and hard.
Most pilots are whingers, let's face it.....
Yes, but only because alot feel powerless against a managment that has been unreasonable in both EBA negotiations and general respect and ability to compromise with front line staff. Resources, lesuire time/min rest, pay, attitude etc all seem to be in a melting pot, unfortunately being driven by LKH's "do as I say" no compromise attitude, which filters through the way managment deal with people in general.
So when pilots "whinge" there usually is more than one reason for it. A small percentage are just never satisfied, but the VAST majority have seen the problems first hand and also more often than not seen indirectly the vindictivness and unreasonable solutions that add to workload rather than produce efficiency.
How do you want management to be more supportive? ....but maybe they can change if they knew how to, if they understood what the front line staff needed/wanted.... ...so what are the answers?
LOL, If they understood!!!! hahahahahahaha they have been line pilots, and in the case of the nfom he still is flying a small amount too, although not as much so flying seems to be "fun" again possibly rather than frustrating? Either way, these people know the issues, but choose to overcomplicate them or in the most ingnorant answer to problems get "accounts" to work a solution instead of common sense approach.....remember the "counting the mints" episodes to name but one example... or the buying a cheap tug off ebay, only for its days to be numbered and more expensive in the long run! Who gets in trouble for these decisions? seems like managment dont, but the frustration is passed to front line crews/staff!
Hmmmm, how can they make it better?! lets see....... how about not fudging around delaying the EBA negotiations and deliberatly stonewalling idea's.... how about providing a better rostering system e.g 4 on 4 off? How about checking managment staff like crews get checked..... accountability on their behalf (Dare them to provide feedback forms for there performance from staff?!) How about not being vindictive and decietful with regards to crew! i.e. Tony Richards case for example...... get that ****e off the websites! How about not berating crew in the friday files!
Where do they start, easy, start on themselves, real change comes from introspection and realistic measurement of performance...... attrition rates and staff morale SHOULD be a major sign to these people that they are not meeting standards! 
Pay, many have said that's not the main reason.
Generally this may be true, but its always a factor. I speak for myself when I say a modest increase in pay and more time off would have had me reconsider my departure. For me at my stage in life pay is important and should be on par (bank managers dont care about how cool your job is and neither do wives and kids).
But lifestyle is very important, rosters in sydney are a joke compared to ADL or WGA. 2 - 3 minrest overnights a week compared to 2 a month for most other bases! come on.....
We get one life to live and working is great, but also needs to be balanced so you feel that you can be normal rather than "the pilot guy" who does nothing else..... yawn.
What can REX do to stop pilots moving? Not much being offered on this thread.Don't get me wrong, there are all valid opinions on here and REX need to do something to stop the attrition, but what?
Nothing on this thread! Man please; this is showing the underlying problem, friction between managment goals and staff expectations. Also balance that up with the conditions in sydney for example and you have a clear indication that peoples viewpoint need to change..... Staff such as pilots, will leave because they are professionals, who work quite hard in maintaining their proficiency to do the job, and as professionals should have a little more appreciation by their employer. Its a two way street and it must also be given back by staff, in which for the most part they do! The problem is the undercutting of wages is a small % of the real problem but alas is still a real problem. Rex need to be competative both dollar wise and lesuire wise as well as ground support.
Its a case of a little too late, the damage has been done in terms of frustrating the staff who have been the backbone of this company.
Even cadets are leaving! What does that say to you? Sadly, if you cant work it out managers then you really shouldnt be managers! Really, What do you expect? You have a business to run but part of being a manager is to be able to liase between business needs and connected to that is valued staff, which result in increased man hours and productivity not to mention moral, which would decrease your attrition rates!
Conclusion:
People are frustrated. Frustration due to resources, rosters, respect, pay and conditions, negotiations, ground support etc.
"A stitch in time saves nine", in which Rex is clearly not very good at interpreting into a business plan.
At this stage, many are on hold files and MANY are looking to go. to stop this from happening DRASTIC change is needed. This either means massive increases in time off or big incentive pay to keep people moving upwards to conditions they definately deserve! Think at least 20 - 30% increase in base salary.
I bet CH really regrets saying "so long as we get 3 years out of you", an attitude that really was and still is short sighted.