What do you mean by looping? And in what way doesn't the nesting of tags work?
Many of the start and closing tags are exchanged separately, which might cause some problems if they aren't closed properly when writing the post. But on the other hand it makes it possible to nest them, so that text can be both centered and bold. Some of the tags have the start and stop tags connected together, in which case it isn't possible to have any other tags inside them. This is especially true for the url-tags and such, which should have anything else inside.
But I haven't changed the way the tags are handled, except for some minor tweakings here and there.