As knc1 said - all your actions on your Kindle are logged with timestamp and all. Is this information uploaded to Amazon I don't know. I bought my PW1 at a retail shop, it isn't registered and won't see a wifi in his life for sure. For me all this EULA of "information and electronic" gadgets has gone too far - Amazon has the "right" to analyze your user logs. I wouldn't have an ereader if it wouldn't be possible to use the device without registering and sharing my personal and private reading habits. Add to this the "EULA" of digital content (DRM etc) and at least for me it isn't easy to enjoy this new media at all (successfull lobbying has made breach of EULA contract illegal concerning state's laws in some respect too).
Now for the "disableing" of USE_ALT_FONT. The mass market seems to be satisfied with simple user interfaces for their electronic gadgets - even with phones/tablets/readers more powerful than some PC not too many years ago most are happy with a restricted set of configuration options but these have to work faultlessly. As an example: Publisher's font (mostly Charis) don't work well so Amazon disables them in Kindle editions (the fonts are still in the file but the css references are canceled). Perhaps many Kindle owners (not necesarely MR-members) tried the USE_ALT_FONT hack, had a cluttered Font Menu, used a custom font which didn't looked good on an e-ink device - and they contacted Amazon support. Given a good number of complaints I can see Amazon being motivated to "fix" the USE_ALT_FONT issue
- and it always be the "close" option.
With Calibre, some plugins (not-to-be-named and Hyphenate This!), various fonts-/margin-hacks (thanks again to all devs) and my PW1 with FW 5.3.9 I'm a daily and happy ereader and ebook user. BTW I fear the PW3 will be more "closed" still.