That's true Duvet, the Irish famine is another good example where the term is sometimes used.
Even among scholars of genocide, there is a fierce debate about the best way to define it -- if you look at genocide research, you will see these very robust arguments going all the way back to the 1940s. People have been criticising the legal definition since its inception (for example, it does not include mass killings based on political identity, thus excluding the millions killed by Stalin and Mao).
In recent decades, scholars have suggested typologies of genocide -- basically, that there is not one narrow type of genocide, but different kinds. These often include a category to account for long-term colonialist and economic exploitation, where 'intent' needs to be interpreted somewhat differently.
We should remember that at the time the legal definition was crafted (1948) the major powers of the day had a vested interest in making sure the definition was so restrictive that it could not be applied to their own actions. This legal definition endures but it is by no means the only definition, if we look at what scholars and historians say about it.
My own opinion is that if you have a term that is meant to apply to the most extreme and horrific cases of mass killing, but people don't want to apply it to certain cases that are among the worst atrocities in history, then we should certainly have a debate about definitions. This can be done in a way that doesn't water down the impact of the term.