Gloomleaf is actually a very good counter to the goblins. They need all the combined health they can get, and stealing their armor and attack is rough. Combined with sunweaver able to buff gloomleaf even more and help to keep it casting that is a pretty lethal combo. Focus on green matches as that will both charge gloomleaf and starve the gobbies. Don’t miss any 4 of a kinds, you don’t want to feed them any mana you don’t have to. Watch the skelly though, creating skulls on the board with those attack numbers could backfire. Of course that has always been the risk of skelly. Wait until you have destroyed their attack numbers a bit with gloomleaf before you go skelly crazy.
As to your first points, I don’t think they are going to kill the game, but any change like that is bound to sting a little. The economy had to be adjusted to keep the game profitable, something we should all want.
Your second point is largely incorrect as stated. The goblin set bonus that team gets is +10 life and +4 attack. Feel free to subtract those numbers out and you will still be left with some freaking amazing goblins. Their team bonus is largely irrelevant. To give you some idea, for the goblin it is 1/5th of its health and 1/6th of its attack. Those are drops in the bucket. Your own gloomleaf unbuffed deals 1.5 times as much as the bonus any single goblin received. Unbuffed you kill each goblin in ~ 3 to 4 attacks. After two attacks their teamwide bonus is basically gone. What you are seeing primarily is ascension and global kingdom bonuses. Those would apply to any team this player chose to field. The goblin set bonus is far from broken, the global and ascension bonuses are completely broken but since everyone can have them (eventually) I guess that is fine.