Editors frequently try to remove the double space after the final punctuation of a sentence. This is a recognised style and is not proscribed by the Manual of Style (see MOS:DOUBLE SPACE). The following was originally posted as a reply on a user talk page.
The spaces are not essential, but neither are they redundant. When I learned to type properly (a skill which few people have nowadays), I was taught to place a double space at the end of a sentence. This is done to improve readability. Now I know that in all mainstream browsers these will be rendered as single spaces, but in the wikitext editor, and for anyone copying the text to a text editor or some other application, that is not the case. Wikitext was originally simple, easy to learn and understand, and had only minimal visual impact in edit mode. Nowadays, the wikitext is usually littered with templates, some of them exceptionally long. It has become almost impossible to actually read the article in the wikitext editor. Anything that improves readability has got my vote. Additionaly one can search for the double space to find the sentence boundaries.
I am sometimes accused of applying my own invented standards. Here is what the MLA site had to say on this: "As a practical matter, however, there is nothing wrong with using two spaces after concluding punctuation marks unless an instructor or editor requests that you do otherwise." Here is an informative article from The Independent.