I am not one to rant. However, I would like to semi-rant about why Shaymin EX is not a format destroyer.
First off, Shaymin EX marked a point in Pokemon where you started to leave casual play and entered into competitive territory. Decks can play and perform well without Shaymin, except for a select few. If you're a casual player you can simply choose not to play those (Example: Mega Ray, Despair Ray, etc.) decks. For someone like me who wants to get good and be able to perform well at tournaments, I knew that the first step was to invest in some Shaymin. Just a disclaimer: I may be 14 however I provided the money for the Shaymin so they weren't just handed to me. Getting them was a trial but I knew that it would be a step in the right direction.
Secondly, Shaymin EX didn't make the format bad or unbalanced. I don't have much to say about this, however if you want to see an unbalanced format, go to your local Friday Night Magic scene and watch the standard. You will see the same 3 decks played all across the table, I guarantee that.
Lastly, a rerun of this set is not as bad as you think. Yeah TPCi may be printing money by printing more Shaymin. However, this will make them a bit easier to find. With more Shaymin being injected into the trading scene, the price will go down at least a little bit. When all is said and done, at least Pokemon isn't slapping the Legendary Bird trio onto blister packs just to sell into the Pokemon Go craze.
Soooo yeah. That's just my own opinion, obviously, but honestly I don't think this is too big a deal besides more Shaymins being on the market.