I understand your frustration, but I have read that there are moves being made to improve the rejection emails that are being sent out. But, despite this, I do have sympathy with the screeners in this kind of situation. Often on this Forum they (i.e. the site) are criticised for the length of the queue, and yet people are also asking for actions from them that will doubtless take up a lot more of their time - such as more detailed and 'instructive' rejection emails. I am also not aware of any new standards being enforced.
It seems much of your upset relates to not feeling clear what is exactly wrong with your photo, and your feeling that other photos that are 'worse' have been accepted. I think this latter point is less to do with standards and more to do with consistency, which has been debated a lot over the last few days here on the Forum.
Whilst I agree that more informative clarifications of standards required and rejection criteria - all easily found for uploaders in the same place - would be nice, I do agree that a close examination of the database, together with regular examination of this Forum, are very instructive.
Given my understanding of how things work here, I too would have rejected this photo for badquality. For me this would be because there are a number of issues present - some maybe more significant than others. I will give you a brief summary of my own view - but do remember, I am not a screener.
* Personally I would prefer a crop that had the aircraft lower in the frame and did not cut off the top of the tail. I know people have different views on such issues, but I think the photo would look more balanced that way. Thus the fuselage would not be placed centrally (as in your shot), but when you look at the complete aircraft it would be more centred.
* The aircraft does not look sharp overall - I think this is particularly noticable towards the rear, where things look just a bit soft.
* I feel there is a difficult to define lack of clarity to the image - hard to describe but, for example, I would like to see that red navigation beacon 'sparkling' more.
* The lighting/exposure looks wrong - the shaded areas below the aircraft looks very dark.
For me, with these areas in my mind, if I were screening the shot, a rejection for sharpening would not suffice, nor would one for badexposure. That is why I would support the use of this rejection criteria in this example.
I have taken a harsh view on purpose, but with the aim of being constructive. I hope you find the above of some use.
All the best.