It seems this topic is largely directed towards me or my statements so in my defense:
If a listener's/DJ's/producer's taste evolves and matures, that does signify that he/she was listening/playing/producing "basic" and "immature" music. Tastes change over time, not to the point of inconsistency, but they change naturally, and any resistance to change would be a crime committed towards oneself. My taste evolved from Hard Trance & Uplifting Trance in the late 90's to Uplifting Trance and Progressive Trance in the early 2000's - that doesn't mean Hard Trance became "basic" or "immature" in my eyes in the early 2000's!
If my taste remained the same as it was in 1999, I would be only listening to Gouryella and Out Of The Blue now, ignoring fresher Trance sounds. Some people's taste evolution takes a narrow direction within the same genre such as within Trance subgenres only, others' evolution takes a wider direction within the same sound such as within EDM genres only, others' takes an even wider direction beyond EDM, etc... This is only natural. Evolution is the reason why anything, from life to art, survives over time. If Trance hadn't evolved from the 90's till today with its DJs and producers' tastes evolving, Trance wouldn't still be one of the biggest EDM genres today.
This is not about being "mentally wise" or "leaving that immature kiddish style". It's much less extreme than that description: it's simply acquiring a newer, wider taste in music. For example, I've been a Trance fanatic since 1999 for many reasons, while the main reason has always been that I never found better melodies than I did in Trance music. The feeling that good Trance melodies used to stir in me is something that high BPM Trance doesn't manage to stir in me anymore (while most Progressive Trance still does it for me). This is not a rational decision I made to stop enjoying Trance and start enjoying something else. It happened naturally, beyond my will or control. So why should I resist it just for the sake of remaining a Trance purist? I've done more Trance in 10 years than most of the people I know (except SamEr & samlbronkowitz), but today in 2008 most Trance isn't doing it for me anymore for reasons that are beyond me - should I stick to Trance just for the sake of my legacy? I began exploring outside the box and found what I need in other melodic genres. The basis of my taste is still there: good melodies. I now find these good melodies in Melodic Techno, Progressive House, and Progressive Trance.
It's an entirely emotional issue, not a rational one that we can dissect.