Sorry. Nothing could be further from the truth, Pugachev. Many iPod users loaded other content on their iPods and NEVER went to the iTunes store. . . ever. I do not believe I have ever purchased a piece of music from iTunes. So your characterization is totally wrong. Apple provides tools to convert almost every type of file. The number of file types that can be loaded and used is quite comprehensive. iTunes supported audio formats include: MP3, AAC, AIFF, WAV, Audible .aa files and iTunes purchased M4A and M4P music files. iTunes can convert between MP3, WAV, AAC, AIFF, Apple Lossless.
One does essentially need to use the iTunes App to load the files, but the iTunes Store is just a portion of that App, it is not required to purchase anything from it, or even visit it, to use an iPod, iPad, or iPhone.
Other MP3 players I've used in the past, some of which do store amounts comparable to an iPod, like the Zune, do not have the file organization qualities nor the sound quality of the IPod or the Sony devices.
That is certainly true.
I would estimate than not less than 25% of my MP3 files do not convert to iTunes. I’ll take your word that Apple offers a variety tools that might overcome the problem, but why do I have to spend the effort digging them out and using them? Why doesn’t Apple just allow MP3s to load onto their players? Sony and everyone else does. Why require iTunes at all? It isn’t that iTunes is a more audiophile format, it’s only because Apple want to make it easier to get you music from iTunes, and harder to get from elsewhere. That theme seems common to all Apple products.