It does feel that way. Did someone on the creative end leave the show part way through?

Yo, that link broke!

I agree, the Decade designs are fantastically bizarre and hyper modern (When I thought Decade was the weirdest Rider design, DiEnd comes along). If only the writing rose to the challenge.

The first episode

Yes, actually. The head writer changed at some point (halfway?). Unlike Hibiki I've never really heard why.

I'm pretty sure it only being 31 episodes was just a conscious decision on Bandai's part to stagger the new Sentai and Rider shows each year out a bit more for markety reasons too, so I'm really lost as what exactly caused them to switch things up like that. I don't think the show was doing poorly or anything.

Why do Toei always kept the identity of actor who play Kamen Rider a secret?

For Example, They kept the identity of Kamen Rider Sigurd, Kamen Rider Proto-Drive, Kamen Rider Dark Drive, Kamen Rider Necrom and recently Kamen Rider Genm who have no spoken line in this week's episode a secret.

Kamen Rider Sigurd's identity was Lock Dealer Sid

Kamen Rider Proto-Drive's identity was Chase

Kamen Rider Dark Drive's identity was Paradox Roidmude who was disguise as Eiji Tomari

Kamen Rider Necrom's identity was Alain

I think Kamen Rider Genm's identity is most likely to be Parad since the set leak about Ex-Aid was true because they says about The President of Genm Corporation was a young man and it says Kamen Rider Genm is to be Higher Up Bugsters. Who is this higher up Bugster? Parad!

Why Toei make a big deal of keeping the actor's identity a secret if you guys knew who is going to be Kamen Rider?

Because Sid appeared in episode 1. Sigurd appeared in episode 14. It was kind of obvious that they didn't want you to know who was Sigurd 3 months in advance.

Because there's this thing called mystery. Not everybody scours the internet and looks up rumors or photographs, especially not the intended target audience for the show; children in Japan.

[sarcasm?]Dude spoilers![/sarcasm?]

But really, I'd hardly call it a big trend. Ghost in particular didn't actually do anything like that. You see Alain holding the Necrom Eyecon at the end of the episode before Necrom debuts, and despite it being a secret to the characters, Specter is credited as "Fukami Makoto" from the episode he shows up.

To build up hype and suspense. It makes viewers theorize and if it turns out to be true, then people feel nice and fuzzy inside due to being right. It's a common thing in media

Why didn't they tell you that Darth Vader was Luke's father (hey, you never know...) from the very beginning?

Because we technically came into the series in the middle of everything. If they had actually started at episode one and gone forward, we would've already known that DV was Anakin.....