I admit it. I'm a format snob. I'll buy mass markets without a thought. I'll pay hardcover prices for a book I don't want to wait for. But I rarely, if ever, even LOOK at trade paperbacks.
Part of it is the price vs. value proposition for me. Trade paperbacks are still paperbacks. They are not made sturdier (in general) than a mass market paperback. They are simply bigger. And are, in some cases, double the cover price of a mass market. There's no additional value for the increased price.
The size is also a factor. Trade paperbacks are uncomfortable for me to hold. Hardcovers can generally be rested on my lap. They stay open easier. (Not to mention that they do not suffer the insta-damage of spine creasing that paperbacks do.) Trade paperbacks must be held open. And I have small hands.
The biggest reason, though, is that I tend to mentally equate trade paperback books with literary fiction. It's most likely a leftover reaction to all of those Oprah books I had to shelve when I worked for B&N, but I don't think of genre fiction when I see a book in trade paperback.
Even knowing how inaccurate that assumption is (Chick Lit and Erotica have long been in TP format), I can't seem to overcome it. And I don't think I'm alone in this knee jerk reaction, either. Although big box stores like Walmart and Target are starting to stock trade paperbacks, most grocery stores in my area are still mass markets only. Which makes sense given that mass markets were designed for mass sales while trade paperbacks were originally intended to be a bookstore exclusive format.
Publishers seem to be pushing mainstream authors increasingly in the trade paperback direction. Nora Roberts's Bride Quartet series is the first time I can remember her books being released as trade paperbacks first instead of hardcover or mass markets. (Reissues of her books through Silhouette have been available off and on in trade paperback for over a decade).
I'm not sure if the increase in the use of trade paperback formats is an attempt to recoup mass market losses due to ebooks or if it is simply a trend that has evolved on its own. Another possibility is the use of trade paperbacks to gain market share in indie bookstores who largely shun genre fiction--in part due to the returns process of mass markets (stripping). But I do know that without the book blogging community, I likely would have missed out on some great books by mainstream authors: including Jill Shalvis's wonderful Wilder brothers series because I just don't buy trade paperbacks.
Unfortunately for me, I can't see myself changing my behavior anytime soon. $15 is just too high of a price for me to pay for a paperback unless I *know* I am going to love a book. I'd rather pay $25 and get a hardcover that can withstand multiple readings.