It is doubtful that Jesus is reproaching Martha's diaconal service, since that is what Jesus has just recently pointed out to the lawyer makes a good neighbor. And Martha's hospitality is exactly what Jesus has told his disciples to accept when they go from village to village. Jesus, himself, will no doubt eat heartily of the dinner she is preparing. Perhaps Jesus is gently reproving Martha's sense of martyrdom. Perhaps Jesus is suggesting that Martha keep the meal simple.
Hospitality is important, but so is relationship and communion.
Perhaps Jesus is gently reminding Martha that all people are different. And Mary has simply chosen to take advantage of a particular opportunity in a particular time and place. Seize the day. Mary has taken this advice to heart, and seized the moment to sit at the feet of her Lord and to listen. So often this story is painted as a contrast between doing and being still.