I've been collecting for about 9 years now and
have not really noticed anything different from
back then and now.  Only difference is my taste
and interests have changed.  

Anime cel/sketch collecting attracts the younger
crowd.  And with that, you get the good, the bad,
the drama, and everything else that goes with it.
Pretty much, anything Anime will attract a younger
audience.

I have recently gotten into American animation,
and have noticed that the crowds I have been
dealing with are MUCH older (like people in their
40's and even 70's).

So, it is hardly a matter of things changing from
time to time.  We as a group are always changing,
but it is more of a matter of what we collect.  As
time goes on, many of the older collectors will
move on to more "important" things that they have
to concentrate their funds on.  And the younger
collectors will replace them.