Why doesn’t anything sound worse when it breaks in?
Probably the reason may be similar to why most equipment will sound "better" fully warmed up although that doesn’t really have to be the case. I intentionally used the word "most" since if I say "all", somebody will come in and say "... but, but, but I know something sound worse ... so on". If everything I say has no exception then I am "God".
On the other hand, I am pretty sure (and you cannot argue with me on this) I am much better not "warmed up" at all. And even much better with sip of wine.