BeerBorg

Is there any reason for a beginner like me to collect the trub on my first several batches through the Brew Demon? Do other folks collect trub with their Brew Demon? What's the purpose of this if everything I need for the next batch is in the kit itself?
Thanks in advance.

You can collect the trub in order to wash yeast for reuse.

Washing yeast isn't really all that difficult, but it is time consuming. If you're using dry yeast, it's probably not worth the effort because dry yeast is so inexpensive (and if you're doing kits, there's new yeast in each kit, anyway). It makes more sense to do if you're using more expensive yeast.

I agree with BPG.
I save liquid yeast, which doesn't ship well in hot or cold weather. When I do, I just scoop it from the fermenter with a sanitized spoon into a sanitized jar. If you do this, don't seal the jar tight as the yeast will still produce gas. I keep it in the fridge, and make a starter if it's old.