The power of having a strong and wide lexicon or variety of words is the ability to be specific about thoughts or feelings or ideas that need expression. When a language is changed to limit communication, the expression of feeling or idea is oppressed.
This is happening throughout 1984... ironically, it happens regularly in many pockets of the world. Texting does this today - words become smaller for some. As technology puts more ipods in our ears, tech toys in our hands, and tools to simplify our lives, we spend less time thinking because it gets done for us. We spend less time working because tasks are completed for us. This is the danger of an over-technologized society. This is one of the messages of the book, when we stop thinking, we are susceptible to losing our humanity.