There will always be some temporary files, even if you did a hard reset, it would build up again.
And I don't want to seem rude, but ~84MB is nothing compared to my ~190MB and other people here are even close to 2GB.
But what also eats up temporary storage are the pictures on SkyDrive. You can read more about it here for example (different Lumia, same problem).
But you really don't have to worry about 84MB (hence you have about 32GB (minus the system files) to use.
That post is from 2013, April. GDR2 and GDR3 have come and gone. Then we've had Amber and Black too. So now those files won't ever build up into GBs. They are going to be as relative as temp files on a Windows PC.