Are there any benefits to using more instruments?

Hi,
I have seen many scores on this site that use lots of instruments, for instance, if you search 'Two Steps From Hell' you can find a copy of their song 'United we stand, Divided we fall' composed for a ton of instruments, including three trumpets, five clarinets, and four types of trombone. My question is this:

Are there any benefits to using loads of instruments, or is just using a handful sufficient? When I add a bunch of extra instruments to my tracks it doesn't seem to make much of a difference.