heh...
There is one very HUGE difference between pop and concert hall music:
A. concert hall music (or classical if you like) is made for
live performance almost exclusively (almost, although I've never seen any concert hall piece whose the composer, didn't have in mind how it would be played live, even in electronic pieces, or aleatoric, etc). This means that the concert hall pieces have some "attributes", like
i. sociality (a concert is a social event), which is hugely ipmortant
ii. interactivity between the audience and the performance! This, they are trying to extinct, but I can't admit it happening anytime soon or late!
iii. The chance of an error. We are being taught, as every performer, that the ideal performance is that of a CD! Totally wrong! Many pianists of the past, in the heat of the concert made many errors... Even orchestras. And I'm not talking about ignorance or irrisponsible performers but for real life simple errors, because of sweat etc.
iv. Almost all concert hall music needs to be playable! Ever seen a Sonata that cannot be played? (even so is it even 0.1% of the whole literature?)
on the contrary with pop music your starting point is almost exclusively... the media (tapes, vinyl, CD, DVD most recently). This means that:
i. No interactivity, no need of that
ii. no chance of an error
iii. same performance again and again
iv. listening to winamp is certainly not a social event!
v. No problem in having ANYTHING, no matter how weird or unplayble it is (imagine the aesthetics that can happen in this instance)
etc...
Apart from that (edited cause my kids hit enter)
It is obvious that all is opinion, but here we are discussing the reasons behind your opinion which is really interesting

! As I said I think that I kinda agree and especially after listening to some rubbish Greek pop music here, I can wholeheartily say that it was rubbish, alhtough many people think it is great art... I won't really talk about it to anyone here, but I can "safely" admit it with you and the whole of the public here!

It was rubbish. But of course I'm comparing to British or US pop music (NIN, or Radiohead for example) and not classical music really...
And I would also urge myself to say that "foreign" music is not as successful here as it is outside of the country (in France, or other countries) and this is becasue we have many many Greek artists. So it does make sense in a way, what you're saying. I have to admit that!
but I'm still comparing pop with pop and commercial with commercial...
I'd say that, even if both are labeled music, they are hugely different and are coming from totally different perspectives.