Three points I'll make, two of which have been missed (I think) and one which has been to some degree discussed before.
First, the matter of nullsec alliances and where they live. It's no secret that the 'best' null territory is that with the highest number and value of complexes - that is to say, the places where the most damage can be inflicted on NPC pirate factions. While the sheer numbers of facilities wrecked, ships destroyed, and crew killed are in this day colossally inflated to the point of absurdity, I don't think we should deny the damage capsuleers do to NPC pirate factions either. Every day, hundreds if not thousands of capsuleers happily sit in their null regions and suppress the far more dangerous pirate factions, providing a valuable service to the Big 4 and CONCORD.
Second, there's the economic benefit of capsuleers. Anyone who does industry can testify that highsec research and production ques sponsored by NPC factions are constantly busy; lowsec still has a healthy bit of R&D going on as well. We also pay taxes to the Big 4 and/or CONCORD on our reprocessing, buy/sell orders, repair fees, etc etc - every bit of that is business. Nullsec alliances pay fantastic tax fees directly to CONCORD for the right to claim a system as their own. Unfortunately, this reasoning has been hit by the mechanics-derp hard in recent years - the fees for using those NPC assembly lines, for instance, are really freakishly low - but the concept is there in the original design: Don't let the 'capsuleers are free' lines from the trailers fool you; we are intimately bound up in the empires' economic systems.
Finally, there's the matter of the capsuleer as the tradesman. This is still hinted at in missions, but used to be much more obvious in some of the profitable buy/sell routes for NPC trade orders before they were removed: We have impressive mobility compared to NPC traders, and so form an important step in the Big 4's need for fast (and relatively safe) transport of goods between systems, constellations, even regions. Unfortunately, this aspect has been hammered hard as profitable NPC trade routes were nuked out of the game, largely because they were entirely static (zero skill needed to locate and take advantage of) and were heavily exploited by bot haulers.
I would very much like to see a return of short-term pseudorandom NPC buy orders, which could be taken advantage of by observant players for moderate profit (above the currently remaining, relatively unprofitable NPC trade routes but below the higher-skill/risk/profit business of playing the market against other players) to give the world a much more "living" feel.