What can Gregor do now that he couldn't do before?

Gregor is now able to evaluate his own existential condition by observing his family's decreasing care towards him. Gregor is able to analyze his own self worth, and the fact that his prior existence as an economic contributor for his family was the primary reason why his family valued him. Now that he is unable to provide for them, the family members begin to provide for themselves and pay less and less attention to Gregor, thus he becomes a secondary priority and eventually a burden. He realizes that his previous role as an economic contributor was a superficial aspect of his life, which he had dedicated all of his time towards. Now that he is unable to perform his "duties", he is no longer considered worthy in the family, and his increasing awareness of his worthlessness strips him of his humanity.