You need to understand that this is how the economic business model works. See, most fansub groups, once a series is licensed, drop the series from their list of projects (although there are some that don't). This is because the anime industry is powered by the people who consume the product (in this case, the anime shows), and either watch them on live TV (in the language of your country) or buy the official DVD releases. If you download stuff from unofficial fansubs when there's an official, company-backed release of the exact same stuff out there, you're actually consuming a product illegally (as much as we don't want to acknowledge that, me included).
If Crunchy Roll has gotten to an agreement with fansubbing groups AND with the actual companies behind the series they sub (Sunrise, Bandai, etc.), it's, in the end, to keep the business model afloat. The limitation they put on having only one group subbing a series probably comes from the producing companies themselves, to at the very least reduce the wild illegal distribution of their product and try to make some revenue out of it (considering some series are NOT going to get licensed Stateside anyway, yet they're still consumed by the masses of the occidental world).
In the end, it's all about the money, as much for Crunchy Roll as it is for the production/distribution companies themselves. From me, all you get is this: At least you're getting your anime fix, so don't complain.