THere is, for one thing, a lot of equipment you may not want gracing your living room: a skimmer, for one thing; plus it may create a 'security gap' re fish jumping out of your tank. Some skimmers notoriously spit, and if you're going to have a water accident, skimmers are often involved---I had one brand that belched water on re-start after a power glitch: it was 'in-sump' type, or could be made so---I don't know what I'd have done otherwise. The sump is extra water. It's extra water cleaning. A skimmer is major aeration. You've also got your heater, occasionally the pump for a hang-on ferrous iron reactor (GFO) to handle a phosphate problem...and it's a place to put that cute gorilla crab you're too tender-hearted to kill. Or the fish you NEED to take back to the lfs.
I've run without, and with, and a sump does so many jobs. I recommend about a 30 gallon one for a 50 and upward, though for a while I did manage with a 10 gallon sump. 30 will handle almost anything most people would ever need.
If you have a basement below your tank, you can also put two neat small holes through the flooring (easily patched if you sell the house) and put all the nastiness down where you may have a floor drain.
I've run without, and with, and a sump does so many jobs. I recommend about a 30 gallon one for a 50 and upward, though for a while I did manage with a 10 gallon sump. 30 will handle almost anything most people would ever need.
If you have a basement below your tank, you can also put two neat small holes through the flooring (easily patched if you sell the house) and put all the nastiness down where you may have a floor drain.