Completely agree with this, a well written ruleset should be suitable for both casual and competitive play. Although I completely understand that it's a lot easier to say this than to actually do this when putting a ruleset together... at one end of the scale you have the StarFleet Battles type rules which are massively offputting to new players in their scale and complexity and at the other something so loose that it's open to too much interpretation.
Look forward to seeing this on the site, I'm interested to see what you come up with