Hooah!

The image above is a Facebook post shared by Brian Shotton a while back, and I think it highlights what the MERCS system is aiming to achieve.
The fact that the system can be played by active soldiers shows how accessible MERCS is, and that the system gives players the options to play with minimal set up.

2D Terrain

The rules allow for play in 2D terrain, which gives players the option to play without the requirement of expensive terrain and scenery.
You can use official or unofficial maps, or you could always just draw up you own terrain like I did here, which has the added benefit of being very easy transport.

2'x3'

2'x3' is great size for 28mm tabletop skirmish wargaming, and fits comfortably on most kitchen tables.
This also makes it quite feasible to create entire tables of cool terrain, if you feel so inclined.

MERCS Movement Cards

The use of MERCS unit cards for unit stats, movement, measurement of distances and templates was minimises the amount of equipment required to play. You're already using the cards to refer to unit stats - why not have them serve multiple functions?
Templates and measuring tools can be quite expensive, and having to transport them safely is just another thing to worry about - though I should point out that the release of MERCS 2.0 gives players the option to use standard tape measure if they want to.

Squad Level Play (5v5)

Not many other systems out there require a model count of only 5 models per side, but this really makes the system accessible. You have the option of only having to assemble, paint and transport 5 models to your games, meaning that preparing for your first game is relatively quick.
That being said, if you're like me then you've just gotta catch em' all.

Sync out.