No, you get it -- contaminated terrain is not an advantage; it's a distinct disadvantage. It's part of their lore. It was a big part of Armageddon mode in the first Warlock installment.

I designed the Dremer race to be challenging to play. They are considered an 'expert' race -- high risk / high reward. Their economy is the most challenging to manage, yet they also have racial access to some of the strongest units in the game. Couple that with the fact that a great building like the Biogenesis Crystals and their ordinary towns produce contaminated lands, and you've got some real curve balls to manage.

If you plan your town carefully, you can mitigate the worst of the Biogenesis Crystals. Remember -- it only contaminates flat land, so you can terraform and/or plan your placement accordingly. And a fun tactic is to plant Dremer towns near your enemy cities and sabotage their movement and food production.

So consider contaminated terrain part of the challenge of playing the Dremers (and just think of how much harder it would be without the bonus pack, heh).