The Starman Omnibuses aren't quite as bad some of these, mostly because they were 16 or so issues of content for 50 dollars that Amazon or stores usually marked down to around 30. They weren't really cheap paper if memory serves.
That said, DC's recent run of 'Omnibuses' have left something to be desired. I haven't checked to see if the Teen Titans omnibus lays flat, but the first John's Flash omnibus was the same amount of content as the Starman ones but for 25 bucks more. The page content seems to be getting better as the Hawkman omnibus collects his entire run plus the JSA crossover issues.
That said, my Walt Simonson Thor Omnibus and Alan Moore/Alan Davis Captain Britain Omnibus' are wonderfully put together and some of the best I own.