Why is Sentai expected to take risks but Kamen Rider expected to keep convention?

[Burkion]

Madoka being based on Ryuki would explain a great many thing.

 

[Glamador]

People expect it to be more like Ryuki than revealed so far. Reportedly, Ryuki is Urobuchi's favourite series and he is supposed to have based Madoka off of it (I have no idea whether that's true)

As most of my complaints about Ryuki are on the execution side of things, rather than the concept side, I'm actually really looking forward to seeing it get a redux. I hope it's quite a lot like Ryuki but...ya know...better. Ryuki did, after all, have the best main antagonist in the franchise. If they can improve the acting and the suit designs and the action direction and some of the more idiotic instances of doing-it-for-the-plot then me and Gaim are gonna get on just fine.

I don't care if one Rider series is terribly similar to another Rider series. But if you're going to go that route you invite comparisons, good and bad. Though basing your show off of Ryuki is a good way to look good by comparison in my eyes.

All I really ask is that you explore the concepts and themes that your series presents, instead of leaving them to stagnate and be ignored like Wizard has done. Shows like Fourze and Ryuki and OOO and Double all had consistent, progressive themes that, good or bad, had something to say. Shows like Kiva and Kabuto and Wizard on the other hand, felt like they were just going through the motions.

I don't know if that has much to do with KR 'keeping convention' as the OP says, but it's what I'm looking for in a show of any sort.