Kamen Rider W is similar to Dekaranger (due of having detective theme)
EXCUSE ME! The DekaRangers are a POLICE force. W was a private, freelance detective for hire. One solves mysteries, the other actually has the power to arrest and throw people in jail (and in DekaRanger's case, act as judge and jury). I'd hardly call them similar. Maybe if W had a siren on his head, I'd believe you. If anything, you should have been comparing Drive to DekaRanger.
Kamen Rider OOO is similar to Gingaman (due of having a same writer)
...Really? I seriously fail to see how a triple-changing, nature-powered superhero that fights alchemy-created, 7-deadly-sins based super monsters is REMOTELY similar to nature guardians powered by super space animals to fight evil space pirates. Sure, there is an animal element, but that's hardly enough to make a worthy comparison.
Kamen Rider Fourze is similar to Megaranger (due of having take place high school and space)
MEGARANGER IS ABOUT VIDEO GAMES!
NOT SPACE! I don't know why there is any kind of space-age elements. I haven't even watched the show because I'm waiting for the Shout Factory release, and even I KNOW that it's more about video games than space! How many times are people going to make this comparison?
Kamen Rider Wizard is similar to Magiranger (due of having magic)
I--Actually, that's a fair comparison to make. I'll give you this one, though I feel like MagiRanger was mostly profiting off the popularity of stuff like Harry Potter at the time...
Kamen Rider Gaim is similar to Shinkenger (due of samurai stuff)
...You know, I'm sensing a pattern. A pattern of someone who has never watched the shows but still feels like they know enough to make a comparison. How many differences should I list? How about how only one has a fruit theme, while the other has an origami theme? How about the fact that one was willing to handle heavier subjects like dealing with death and taking responsibility for murder? How about the fact that one pays homage to historical samurai while the other is lazily entertaining the idea of a literal modern samurai? How about the fact that the riders have an armored look from the start, while it takes a giant robot for the Shinkengers to start looking like an iconic samurai?
Look, I'm not going to say there aren't any similarities what so ever, because there are. And if using a small amount of assets helps Toei make the next show, be it the next Sentai or Rider, what's the harm? Because despite sharing a few similar thematic elements, there is still just enough changes that it's not really fair to call them the same, nor is it fair to say one show is turning into the other. I still think some of the "darker" or "more serious" elements that defined Kamen Rider is there. And what's so wrong with changing things up every once in a while? Not everything can be serious or kiddy 100% of the time; that's just boring and predictable.
And even if I thought Kamen Rider and Super Sentai were having identity issues, what's Toei going to do about it? Sue themselves? It's their creation. Let them recycle as much as they want. I'll hold my complaints until a show's story and elements are actually the same, beat for beat, as one of its predecessors.