In short, they aren't trying to change how top lane is played, they are trying to change how top lane interacts with the rest of the game.
Right now, the power creep really started rolling top lane and I believe that Irelia, Riven and Renekton are the main causes. Basically, Irelia came out, with her variety of tools. They built her so that she would've the ability to trade in lane. So a "reliable" cc, mobility to engage/disengage, sustain, and "defense penetration".
Then came Renekton, They wanted him to be on the same page, so they gave him mobility, sustain, trading potential and cc. He was designed to be a tankier and burstier Irelia, with less sustain and "defense penetration" (imo).
Then it's Riven's turn to come out. They designed a champion that would dance around the battlefield while dishing out damage. Getting caught should result in a huge downside. He's basically a huge mobility and trading power, but with little to no cc and sustain.
That, in my mind, designed the holy trinity of top laners, that we'll call the barrier of entry. What that means is that now every champions designed to go top has to eb tanky enough to resist the barrier's damage, has to have enough trading potential to not get bullied out of lane, has to have enough overall poke so that the enemy can't just outsustain your damage... In short, Darius, Aatorx, Jayce, Yorick... If they go top, they all cannot be stopped unless a major slip-up happens. And that "cannot be stopped" transition into a "I will trash your whole team" phase if he snowballs.
For those that are very nitpicky, yes jax is a super strong top laner, and so is Shen, but they don't fit the same "island top" as the barrier of entry. Basically, Jax can be killed and Shen can't be used to full potential without either being really far ahead, or "losing" his lane.
