I've been listening to japanese music since around 2000, and profusely since 2004, and I can tell that every year people say what you are saying. VK represents maybe 3 or 5% of japanese music industry, I guess. It's a niche inside a niche, thousands of bands disbands and forms everyday and no one cares. People go where the money is, so of course 18412980123 newbie bands will imitate what is giving money nowadays. There's always a "phase" going around, if you get what I'm saying. There was a time when EVERY BAND was oshare, then EVERY BAND was linkin park, then EVERY BAND was dir en grey, now EVERY BAND is metalcore. Even the bands you mentioned were kinda influenced one by another.
TL;DR: VK has always been like this. You just don't like the flavor of the month.
liriel reacted to pinkmakona in MH FEATURED POLL #44: Have you ever had/do you currently have a crush on a Jrocker?