Hmm, first
I want to say this. Everybody, no matter what nationality, is defensive when it comes to their home country. Between ourselves we moan and complain , but when "outsiders" do the same, we become defensive. That is normal human behaviour. I am sure Qataris realize what is going on in their country,the good and the bad. Expats have no affiliation to Qatar, other than doing their job, making money and then going back home. It is therefore easy for them to look at what they see,and saying exactly that, no excuses no beating around the bush. Of course, different attitudes, due to upbringing and culture factor into this. What some nationalities see as constructive criticism, other see as plain rude.
And yes, I am sure that jealousy plays a large role in all this. What we see is one thing, reality may be another. As mentioned before, due to lack of cross communication both sides have pre conceived opinions.

Having said all this, it is obvious that it is only a generalisation, as many Expats and Qataris are friends and do talk. But those people may not feel the need to talk about this on QL ;)

Anyhow, I am one of those expats that has Qatari friends from different walks of life , and I can tell you this...they are as normal or crazy as the next person you may meet on your travels or at home.