Why the current riders don't have evil organizations ?

Clearly you haven't watched W or Fourze.

How come Foundation X hasn't make any appearance in recent Kamen Rider?

Some fan call Foundation X the Next Generation of Shocker

But they didn't make any appearance in Kamen Rider Wizard or Kamen Rider Gaim.

Who is to blame for absent of Foundation X? Head Writer or Head Producer?

Because Hideaki Tsukada hasn't produced a Rider show since Fourze and nobody else cares.

man, they really dropped the ball when they dropped the foundation X storyline...

Well they never dropped it since it was never there to begin with. Foundation X was just something in the Double storyline. It was never meant to go on past that one show.

My assumption is they were trying to have it as the Jay and Silent Bob of the second wave of Heisei Riders, but just gave up starting with wizard.

Foundation X was really just a Double thing. They were never used in OOO and its related movies and were only in the Megamax movie after that.

It was an idea by Hideaki Tsukada the producer of Double to have that shadowy orginization but no one else at Toei had any interest in actually making a new Shocker out of them.

Can I get an official count of remaining Roidmude/confirmed destroyed?

ACTUALLY! the W team asked if OOO would pick up the Foundation X storyline, but the OOO team declined.