This is just my own thoughts so please do get more input before making your choice.
I would guess around 90% of hobbiests do run a skimmer on any tank that is larger than 50 gallons.
The obvious argument is made through showing someone the skimmate that a decent skimmer can pull from your tanks water.
This argument is bias, not all systems require/benefit from heavy skimming.
Soft corals and light stocked tanks can run just fine without a skimmer as the bioload is easy enough for the tanks natural filtration to complete.
On heavier stocked tanks or hard core reef systems where what is considered pristine water conditions are required a skimmer is a must.
The heavy stock if in a reef is partially made up from the sheer amount of live rock in a tank. The amount of live rock relative to the tanks volume can do wonderous things where filtration is concerned. This again negates the absolute need for a skimmer on a stocked tank.
A skimmer WILL pull gunk from your tanks water column but it also allows for more wiggle room in averting potential disasters such as spikes in the negative toxins from overfeeding, unanticipated death of a tank inhabitant, ect.
A heavily stocked tank (live rock) will insulate the tanks stability to change because of its own ability to process toxins.
The flip side of the coin is when a tank is heavily stocked (even if well balanced) the tank will be more at risk to excessive loss if excess biotoxin is introduced. For example your curious little blennie finds a secret entrance to a powerhead. Or an anenome goes wandering around into one and shreds itself. A problem that would still be serious if skimmer is in use but the skimmer can minimize the window of danger to the entire system through its addittional filtration.
A regular water change routine is always advised for any tank. A good skimmer can eliminate NEED for waterchange due to toxins. Water changes more become to re-stock trace mineral levels and for maint as they are intended.
I have been off the boards for some time but I do remember several folks running successful tank WITHOUT a skimmer, but it is the exception not the majority.
I personally would not run any tank without one, thats just me.
-RFB