Apple doesn't just willy-nilly throw the i- designation of every product they have, though. i- is a special sub-brand that's used to express something that is small, easy, light, etc. Customers who are familiar with Apple's branding can immediately guess at how an iMac differs from a PowerMac (or, when they still existed, an iBook from a PowerBook) based only on knowing their names. That branding was carried forward, so that the same connotations helped offer consumers an immediate sense of familiarity with the basic idea behind new products such as the iPod, the iPhone, and the iPad. Even now, you see a hint of the distinction alive in iOS vs OS X. They rest on the same technology base, but keeping the distinction alive means users still have an easy mnemonic to help them keep track of the distinction between the two and their relative capabilities.

So yes, Apple does reuse monikers in their branding. But they use them to create a branding language that helps them to better communicate with customers. This is starkly different from what Microsoft is trying to do with the Windows brand, which is to turn the word into a blaring, monotonous drone to be blasted at us until we enter some sort of alternate mental dimension where words lose all meaning and every single noun is replaced with the word Windows.

Apple have been fairly consistent; the 'i' prefix has been synonymous with Apple since the iPod in 2001.

Microsoft chop and change brands all the time, often in ways that are confusing to the consumer and damaging to the business.

Labeling things with -Kit dates back to early NeXTSTEP (1989). I believe it was originally intended as an indicator that a library included an object-oriented API.

Indeed, when I first heard of "Healthkit" I misread it as "Heathkit" even though Apple is pretty much the antithesis of Heathkit.