That is the question, and is applicable to all types of Cricket, and, indeed, all sports. I suspect there are two main, connected reasons. Firstly the English way is to discard "failures" rather than promote "successes". If a player is dropped, it is generally because he has had a bad run, and so the pressure is on his replacement to improve on things from the start; if he doesn't, likely enough he will be dropped himself as a failure. The one consistently worthwhile aspect of Australian selection has been that players, when selected, are presented as being better than their predecessor; they start with a positive, and don't feel they have to succeed straight away to keep their place.
The other factor is that the English are addicted to "Tall Poppy Syndrome", preferring to cut players down to size than to praise. This is so throughout the press (where destroying a player or manager's career is seen as a triumph) but particularly among ex-players. Michael Vaughan is a truly vicious poacher-turned-gamekeeper, who seems to forget the troubles he had as an England player. This is much less among foreign journalists.