ya its amazing with 8 fully upgraded explorers (1 lucky) i'm up to 1.2k eggs. the only reason you were able to get 3.2k is because you were able to "abuse" the bugged lucky explorers. if they would have fixed it since the start almost no1 would have got it at all, but maybe you're right it was great.....
while i can see your point and these achievement shouldn't be too easy, i think it was too much this time. I would have done pvp to get it but why bother as it's riddled with buggs.