My personal opinion in response to many of the comments left. 'Achievements' are achievements, that is they are their own rewards. If you have al all the 'Brilliant's then achievements become a good reason to carry on playing the game, if you want to.
If you don't want to do grinding then fair enough, don't grind. You'll never get the achievements for grinding, but that's your choice and it shouldn't spoil the game for those who are happy to put the extra effort in.
I don't get how the 'Dread Lord' (Kill 1,000 enemies) achievement works? I have tested and discovered this only counts the last map played & the count is reset when you start another map. A there are no maps >=1,000 enemies this appears to be impossible to achieve. Have I got something wrong?