It's interesting that you bring up the point of 
storyline in anime because being an English major 
in creative writing I feel that originality in 
many things today can be a tad more unique and 
not just another form of last years show.  But 
this doesn't mean that I cannot enjoy these 
shows.  I have had a friend once that was majorly 
into originality and he would become literally 
sick if he saw something that was 1% 
unoriginal... I don't think that's toatally 
healthy, not to be able to enjoy something that 
isn't completely perfect.  Nothing is perfect, so 
we've got to be happy with what little "good" 
things that are out there.  As for why some 
people collect cels from certain shows and not 
others, answers will vary with every person you 
ask, because these shows mean something different 
to all of us, right?  In my day, I enjoyed Sailor 
Moon quite a bit, but that was also in those few 
target years-- and I was heavily into the 
original Japanese version, not the dub.  If 
anybody knows me, you'll know that I am NOT a fan 
of dubbed anime.  I'm sure that a good number of 
you have not yet seen the 5th and final series of 
SM; the only series that I can still say with a 
straight face that I like.  haha  But anyway, the 
point is that we like things for many different 
reasons, let it be for character design, story, 
or just something similar with our own lives in 
some way.  When the characters in a story become 
something more than just thought up beings 
painted by some unknown Japanese dude, that's 
when the magic happens, when collecting cels has 
a deeper meaning.  I beleive that's what this 
hobby should be more about, rather than just 
collecting anything and everything that 
simply "looks good."  Heehee, on the other hand, 
I have bought a few cels that just looked neat 
and I had no idea what they were... like the one 
Zetsuai cel that I had in my possession for about 
a month.  haha  But again, people are going to be 
different, they're going to have different 
motivations for why they like what they like.  
It's as simple as that.  So you collect what you 
like, and so will I!  =D