this people is good in their work 
no one suspects .... Picardo!!!!
i mean Jason Cooper

the real reason is that he is the only actor in the show who has what it takes to pull a satisfactory red john.
i´m not his bigger fan but by far he is the best actor in the show. period. that´s enough.

why is Jason Cooper?
red john,... just remember what Patrick said about him since the beginning:
e01s01 patrick answer the questions in the tv show
he tells that thanks to spiritual contact with red john he can make a profile of him
well, we know it´s not a spiritual thing, it´s pure skill
but he needs to make a living so he has this explanation 
but the profile it´s as good as it gets
he is at the peek of his abilities, he can nail it with his eyes closed
red john is a sad ugly guy
that´s all we need

red john is just like as clever as patrick but is not patrick
beside smarts you need the ability to connect with people
you need the personal attractive
red john can reach isolate persons but he has not what it takes to reach people

we know he is in visualize 
right
in the second row
planning to take over but unable to do what patrick or stiles can
unable to lead
he only can pervert
he sure has an interesting relation with stiles
one that include blackmail and worst things

the thing is: 
we know who red john is
please, reveal him in the last episode of this season 
and make next season a killer with patrick not knowing who he is till....