Why are so many modern novels over-written?

I've just finished Jonathan Kellerman's 'Therapy', an L.A. detective murder mystery (2004). Not a terrible book - I've read plenty better, and also a good few far worse. At 550 pages it demands a lot of one's time and (a common criticism I have of a lot of contemporary writing) I can't help feeling it would have been vastly improved by being half the length, while still retaining its salient plot developments. To get down to specifics, do we really need to know in such fine and extraneous detail what characters look like and are wearing at particular points? - both men and women! What does it achieve other than slowing the reader down having to get through all the unnecessary excess 'fat'. One example towards the end:-
He looked to be around thirty, with long, wavy, brown hair parted in the middle, had on a grey shirt under a cracked, brown leather jacket rubbed white at the pressure points, rumpled beige cargo pants, white running shoes.......(yawn!)
Now what would be wrong with - "He looked about 30, long brown hair and wore a leather jacket and cargo pants."? There you are. It's all we need to know, perhaps even more than is necessary - and it doesn't slow down the action nor lose any atmosphere. I'm only surprised that the author didn't also go on to describe the colour of his underwear!
And why do we have to be told exactly what they are eating all the time? Does it really matter? Where's the relevance to the story? None. If it's junk food, fine, it's junk food. If it's in a restaurant I don't want to know of what each course consists.
I wonder if all this padding is deliberately to make the book longer and so give buyers a feeling of getting their money's worth? (Do long novels sell better than shorter ones?) Otherwise wouldn't the editor and publisher recommend pruning the manuscript offered? There may be something in that, as books of under 200 pages long are often priced the same as one which is two or three times the length.
Anyway, I got through it all after several sittings, but found my impatience to reach the end was getting the better of me and reduced any enjoyment that I was getting, though there wasn't much of that anyway. (Oh, those days when one could read a complete novel in just one sitting of two or three hours!)

Well, I've already started my next book, a re-reading of Roddy Doyle's 'Paddy Clarke Ha Ha Ha' which I first read in 1994 a year after it had won the 'Booker' prize (Britain's most prestigious annual award for new fiction). On first reading I just couldn't get onto the writer's wavelength though this time, after 50 pages, it's going a bit better. But in any case, at a mere 280 pages long, it should be a relative 'breeze'!