I totally understand you wanting to move away from iTunes. The reason why most DJs still use it are simple: iTunes does store your music away very nicely and in a way that it is easy to backup and recover if must be as you simply backup the media folder and iTunes Library.xml and your files and playlists are safe.
Secondly iTunes has a lot more features when it comes to “smart playlists”. Now especially Rekordbox and Serato are catching up with their smart crate features, but there are some that are still missing. If those feature are not needed by you, then you are fine just doing the playlists in your DJ software.
The next thing for us older DJs, we still have and are still getting CDs from labels for free. Hence we need to rip them to mp3s before we can play them. iTunes has a really good encoder (especially if you work on MacOS) and automatically fills in all the id3 tags you need. Filter it through MIK and you never need to edit a tag again.
Now such things can also be done by other software of course, but it is way harder and more cumbersome. I am totally on board with you, I am wanting to move away from iTunes too, but I have not found a solid alternative yet.
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