for one very simple reason. they don't want to go back to the wild '90s when it was free for all and they had an insane amount of corruption. you mention people exposing corruption and getting arrested which is true but then again you also have people who get away with exposing corruption (take Sobchak for one) and nothing happens to them. if you for example are referring to Navalny let me tell you that the Russians themselves are very skeptical of him and his intentions. also,
Russia is the kind of country where the next leader is usually worse than the one before him, so Navalny is no guarantee to be better. p.s Navalny might appear as the cute human rights puppy he tries to portray himself as but he is far from that actually and his stance on immigrants is racist at best

)) and to be clear immigrants are not the lovely sparkling EU/American/Canadian ex-pats here, but the workers from the post soviet republics....
also to be very clear any Arab spring-like movie in Russia will end in a catastrophe due to Russia's immense size. not that the arab spring was that good.. as you can see it was a shitty spring

)