This has already been mentionned on other places I think, but maybe not on this forum.
The reason is simple :
At first, the site was in French only, with French titles only.
Then we added an "English Title" field.
But at that point, the way the site was made, all was written in lower case with the first letter in uppercase, or something like that. I do not remember exactly why, but it was for a technical reason I think.
Well, when we remade the site structure some day ago, all previously listed movies were imported, but not updated. Later most of them were update to put the english/french/original titles in good field, but case was not always changed. And titles that did not had to be modified for their title were not modified for the case either.
So do not hesitate to modify English titles when they are wrongly written. I do that sometimes, as do some other members.
All the new titles that I add are copy/pasted from IMDB for the correct case. I guess that most of the members to the same when adding new movies (but often a "added" movie is just an "old" movie with new cars added on it).
The only "problem" with these rules is that it depends on the language, see
http://www.imcdb.org/movie.php?id=51604 (the part in English repeats what was said in French)