I think people were craving Standard mostly because of Dr. Boom, Piloted Shredder, and Mysterious Challenger being goddamn everywhere.
Dr Boom, Piloted Shredder, Shielded Minibot, Sludge Belcher.
Those cards are the reason Standard was implemented. MC was super annoying and probably way too good, but the stuff from GvG and Naxx being in literally EVERY DECK for over a year and half is why they did what they did. It makes sense. Other card games rotate their cards as well not only to keep the Meta interesting, but to keep the money coming in. When you made a deck (and when you currently make a Wild deck), you think first about the most overpowered cards. Nearly all of them are Deathrattles and nearly all of them are from Naxx and GvG.
For as much as I am pretty unhappy with the Standard meta atm, I really think the move to a format like Standard was inevitable. They had to do something to keep the game fresh after their realized that it was basically impossible to improve on the power of the GvG cards without constant, insane power creep in every set.
I don't really think Blizzard was right to do what they did by keeping Classic around. They could have rotated out some card from classic and put in cards from Naxx/GvG that were leaving into the Classic set. Wild could still have access to everything, but keeping some of the balanced (or fun!) tools that existed in those sets would have been beneficial IMO. Imagine if priest still had Dark Cultist in standard! I'm sure there are other ways than this too, but I still that this makes the most sense.
Overall, the game is in a bad spot in the meta, I'm hopeful that ONiK will bring at least a couple new decks. An aggro/midrange Beast druid would be better than 0 druids on ladder atm. Some discard variation of Warlock could be a fun twist on Zoo. I sadly don't see this exp elevating the Dragon Priest to competitve level. But it might be slightly better. Oh well. I'm not paying for it. So its only gold.