Most big box bookstores don't have as much variety or depth as we've come to expect from exposure to online book sellers. You have to go to a sizeable used bookstore to get that (famous examples being Powell's in Portland and The Strand in NYC).
The problem is that people have diverse interests (niches) and a typical brick and mortar retail operation simply can't afford to carry much depth in any particular niche. The result is a lot of niches shallowly represented, at most big box stores you can't even find all of the books written by a given author, even famous ones, unless they are insanely popular at the moment.
Ironically I think in the next few decades the pre-internet trend will reverse and independent used bookstores will stick around longer than the chains.
I don't think this was the problem with Borders. With Borders, the selection was just poor. There are canonical books on many topics. If you went into the computer section, you wouldn't find things like K&R, Stroustrup, etc., but the latest and crappiest C and C++ books. The same thing was true of books on most topics -- music, photography, sewing, etc. -- there are classics, and instead of carrying those, Borders would carry Dummies and other books.
If you went into the sci-fi section, you wouldn't find Philip Dick, Stanislaw Lem, or even a decent selection of Asimov -- you'd find a bunch of sci-fi books written the previous couple of years, and in many cases, sequels without the originals.
Finding books of quality at Borders was hard. I'd often want a book, go in there for half an hour, and find nothing. The value-add of a good bookstore is that they will have pre-selected the best books for you. If I go many of the little used book shops in my area, it will be a rotating selection of excellent books. Not every book will necessarily be my style, but every book on the shelves will be great, and there will be books on most topics. This is much more useful.
I don't really understand why this was the case. Borders ought to have economies of scale, and really ought to be able to have some central office somewhere picking out good books. Somehow, the selection was random and crappy instead.
I think part of the problem was that Borders probably went the route of overusing metrics, and providing more books similar to the ones that sold, which lead to a bunch of crappy books on popular topics (where it's much more useful to the customer to e.g. have the top 3 books on videography than the top 3 books, hidden in a bookcase of crappy books, where the good ones take an hour or two to find).
The problem is that people have diverse interests (niches) and a typical brick and mortar retail operation simply can't afford to carry much depth in any particular niche. The result is a lot of niches shallowly represented, at most big box stores you can't even find all of the books written by a given author, even famous ones, unless they are insanely popular at the moment.
Ironically I think in the next few decades the pre-internet trend will reverse and independent used bookstores will stick around longer than the chains.