I essentially agree with your position RiA. The reason I am getting rid of these CDs is that I no longer listen to them and so there is no need to have the actual material component anymore. The digital version will suffice, though I don't even believe that to be necessary. In general though, I'm not getting rid of EVERY CD I own. I'm just trying to simplify and only keep the records that I find deeply moving and essential. A lot of us here have a "collector's mentality", not only in music, but in other aspects of our lives. I realized that most of my collection was filler anyway and even if I still had an interest in metal, I would still feel it necessary to trim down to less than 25-50 CDs. Having 400 albums started to seem absurd.
I'm gradually working in this direction in all areas of my life. The only real possessions I want to have aside from essentials for living are some basic comforts such as this computer that are extremely beneficial for information and communication. I'm not on some ideological crusade or anything, I just realized I don't need that much and want to live a more basic life. I'm still going to have a lot of books because I think they are about the most valuable things in existence. I agree with you that things such as music and books are not truly material and perhaps we shouldn't rush to shed the material component, I just want to own them more in proportion to my needs and how I can practically use them in my life rather than to just have a bunch of albums I didn't listen to sitting around.
In general, I'm trying to make gradual changes to get rid of excesses in possessions, money, habits, etc. I'm personally not striving for the complete renunciation of all possessions, only attempting to find a practical middle way.
I also wouldn't say that this is a phase of some kind, but something I've been gradually working towards and implementing over several years. I have a great respect for and appreciation of the musicians of the metal genre and the impact their music had on my personal growth. For me, I've moved away from it and no longer identify with the sounds of the genre, nor the cultural and ideological aspects that sometimes become tied to it. In no way do I feel I've "grown up" from some adolescent phase as some outsiders might perceive it. In my personal, individual evolution I've simply branched off onto a path that is more fulfilling to me.
One thing I believe we all can agree on is that art in its various forms is an essential of human existence and we can all find out individually how to implement that in our lives. Outside of the mediums through which that art is conveyed, and the essentials of living, acquiring knowledge, and communicating, little else is worth having and only works to tie you down.