Reading trilogies or standalones

There is an interesting conversation going on in the comments section of Matthew Cheney's review of Princess of Roumania about how some people just can't read trilogies. Cheney points out how he has given up on one after another:

I think I have trouble picking something up, putting it down, and returning to it—once a book is finished, I want to be done with it. I hate partial anything. It annoys me with new books, because if I’m going to invest the time and money in a book, I want it to be a complete experience. Oftentimes, I think publishers and writers are just trying to scam as much money out of readers as they can, and I resent it. (Though I realize it has a long, long history, going back to the earliest days of printing. Venerable tradition never stopped me from resenting anything, alas...)

I have to say I agree with him. Although, I think I'm more afraid of them then resent them. In my teen years, I read plenty of trilogies: Tolkien, Brooks, Wilson, Asimov (though his books don't quite fit Cheney's complaint) and Adams. But now that I'm older and I find less and less reading time, I look askance at these long, multi-volume series.
Right now, I have books from George R.R. Martin, R. Scott Bakker and Kij Johnson, sitting on the shelf being avoided. I feel like reading one ties me in to reading the rest. It took me years to read all of the Memory, Sorrow and Thorn series by Tad Williams. It took a shorter amount of time to read through Gene Wolfe's Book of the New Sun. Even Jeffrey Ford's Physiognomist Cley novels took me a while. I know there is plenty of enjoyment to be had in these books and there's a lot of fun being held on the line waiting to find out what happens next. But I'm put off, right from the start.
On the other hand, like Cheney, I'm not put off by standalone novels set in the same place. I've read all of China Mieville's Bas-Lag books with any worry, and those are equal in size to any fat fantasy novels you can think of.
This also has me wondering, why do so many authors write such long books these days? All my science fiction and fantasy novels from the '50s and '60s and even into the '70s are short. In fact, I'm reading Jeffrey Ford's "Cosmology of the Wider World" right now and that's about 170 pages, and it's called a novella. Yet, that is about the size of most of Philip K. Dick, A.E. Van Vogt or Fritz Leiber novels (taking three authors at random). What happened in the '80s that made publishers start seeking out the longer and longer novels. I'm not exactly complaining, but it does seem strange to me.
UPDATE: This post at Metaxucafe goes on a little bit about long books (not anything about trilogies really, though the root cause for avoiding both is the same). Despite my worries about reading longer books or trilogies, I can't get behind abridgements. I just don't think you'd be getting the real novel. I've heard of people who read "Moby Dick," skipping the parts about whales. I don't blame them at all. But I can't read that way, and unfortunately that means I haven't finished "Moby Dick," which drives me more crazy than not having read "Ulysses." I see "abridgement" on a book, I think, well I'm not getting the real deal.