Also it's economics that play a part - the reason there are German and French translations in the game is because they're the two main economies in Europe (larger than the UK even) so there is a far greater economic incentive to SE to support those languages in the game, and English is considered a de facto world language.

Unfortunately Spain's economy is not as large as their neighbour, and even many of the countries of South America where Spanish is spoken as an official language... are in economic turmoil, so the financial burden to SE is probably considered to be just too great I'm sorry to say.