Live rock in sump -yay or nay?

Yes I know I can read up on it, and I have, but I want some real life
opinions here.

Brief background, since most of the regular posters seem to be
following my adventures with some regularity:
72 gallon bow, about 100lbs of live rock, 4 inches of argonite sand
(give or take) over most of the bottom, 15 gallon sump, protein
skimmer etc, 10000k flour bulbs...basic newbie setup...

Now what I've read alot of is that it is absolutely crucial to get
some live rock down in the sump, along with a separate lamp so that it
can grow algae, caulerpa etc. I've also read several tales of people
having no problem WITHOUT adding those things to the sump....so my
question is this:
How do I know if it is necessary to get some live rock and light down
there as opposed to leaving it be? It seems that I already have
plenty of rock in the tank to allow for adequate filtration (at least
at this point...my bio load is EXTREMELY low with only one teeny
clownfish and one PJ cardinal)...aside from that, a small chunk of
zoanthid and some large, unidentified, brown mushrooms.

So, am I a candidate for needing the extra hardware? I don't mind
adding it, but I'll tell you the basic reason for asking rather than
just doing...the base for my tank has a glass door, and adding a lamp
will, obviously, cause that glass door to be quite see through. While
I can add a pad or osmething to the door to block that, I'd rather not
have to start futzing if I can avoid it...

Suggestions? Comments?
Thanks,
Mitch