Nope, the main point is to be consistent.

If ALL links are to the index page name it's not a problem. The issues start when some links are to the root without a index pagename (site.com/) and some links include the pagename (site.com/default.xxx) and both versions deliver the same content.

What Hirst said. The reason I made the comment is because /index.html and / have the same content (likely because they're the same page).

So...make the main point consistent. At this point, you'll probably have to do a little .htaccess work to 301 /index.html to / as well (I'm not an expert on .htaccess, but there's plenty of info on this board about it.)