When we serve others, we often do so in expectation of personal benefit... The senses of connectedness, worth, well-being, and so on, that can arise. Not to mention the visceral appreciation of others' lives by serving them individually. Personal service to others is vital and worthy. Please do not minimize it.
A key value to consider in all efforts is their sustainability. An effort that does not nourish the altruist should not continue. Merely emphasizing maximum instantaneous benefit to the recipient does not maximize long term benefit of the needs of the altruist are not also part of the equation.
I'm grateful for some related content in the FAQ referenced here. But I believe if you're going to examine our whole system of altruism, you need to view the servant as part of that system.
I commend to you the book Standing at the Edge by Joan Halifax for lots more about sustainable service.