[Nook Touch General] bobstro:
You've confused yourself by thinking all improvements have to be made to reading. Even in reading, though, there is room for improvement. The stock NOOK reader and library have a lot of limitations and problems:

Limited font selection.

Poor and fragile organizational capabilities with large collections

Mixed support for metadata in sideloaded, non-B&N content (e.g. covers, book summaries)

No support for synchronizing reading positions on non-B&N content.

Removed page numbering from table of contents.

Dropped support for Discover and Popular Science magazines.

I also got tired of B&N deciding that, because I hadn't purchased anything from them lately, I must be interested in novels with shirtless dudes and plastering them on my home screen. The first thing I did after rooting was replace the B&N library and reader with Mantano Reader Premium, which together with their cloud subscription service, keeps my reading synchronized across 5 devices, regardless of where I bought the book. Mantano can also read the newest Discover and PopSci formats with no problem. Mantano also supports additional dictionaries. I find the reading experience on my "Mantano Simple Touch" vastly superior.

Of course, there's the usual litany of performance and battery improvements:

Improved control of wifi usage and automated daily sync using Tasker. Wifi only turns on for the few apps I use that need it. No more leaving wifi on overnight by accident and finding battery down.

Improved control of wifi access using WiFi Manager. Much easier to search for wifi options.

Ability to log into captive web portals (e.g. hotels, airports) and automate login process using Wi-Fi Web Login. Unit can wake up at night and sync without manual intervention to access wifi.

Overclock, multitouch and fast screen modes (I don't use these much personally, but they work well with no perceptible battery impact.)

Automatic sync to local timezone using Clocksync (useful when traveling).

Improved keyboard with Smart Keyboard Pro.

And the usual litany of app selection:

Improved browser (Opera Mobile).

Corporate and private email (Touchdown, Maildroid)

Automated Dropbox folder sync (e.g. nightly news subscriptions using Calibre) using Dropsync.

Offline web reading using Instapaper with Instafetch client.

Travel info (Flight Track, TripIt)

RSS news feeds (NewsRob, My6Sense)

Google Voice (voicemail transcriptions as text).

And a few time-wasting games that work well on the eink screen:

Shredder Chess

Yukon Gold (there's an eink-optimized version here on XDA).

Crosswords

My question to you is, owning a device and having such capabilities, why would you NOT root it? A better start might have been to simply ask what people are doing with rooted devices rather than questioning the need to do so because you don't understand why. I can literally sit at the beach in direct sunlight and do these things (depending on wifi, of course). Why would I carry another device to do these basic tasks when the NST I already have does them just fine, anywhere, indoors or out? Do you find it more sensible for a corporation to define how you should use the device you paid for?