Another benefit to the pan that I didn't see mentioned is the noise reduction. I have my first MB and I thought it was there most for noise shielding.
In fact I just remembered where I got that idea. The marketing catalog for my '87 TD calls the belly pan "a system of acoustic encapsulation". I know my uncle always comments on my car's quiteness compared to his '84 diesel.
I have found the pan frustrating when dropping tools and parts down from above. It seems that lately there hasn't been a job I've done that didn't require removing the pan for this reason.
At least with the topsider oil changing isn't one of them.
'87 300TD 304kmi (RIP)
'95 Toyota Camry Wagon 125kmi