Orgs are there to help people share their ressources to achieve big projects.
Nothing stops you from only developing your character / asset and not taking part in other's project.
"You wanna know why corporations exist? To protect the owners from personal liability and lower tax", again you oversimplify : corporations exist to protect shareholders' interests of course, but why do they need protection ? because they invested their equity in the corporation in the first place, thus sharing their resources with other to achieve a goal, usually get more profits.
Incorporating alone makes sense IRL, for the reasons you gave, but it does not really makes sense in DU.
Also, RDMS are already there to protect your rights over your org. If your org do not compensate you enough for resources you give, this is the problem of a specific org, not a systemic problem. You make it seems that giving away your resources to an org does nothing for your character, but it should give you access to services and facilities hard to come by playing alone.
Most goals in DU are achieved by orgs, same as most Raidboss are downed by guilds in other MMO.
What you would want to change in the org system to make it more character-centric ?