Shooting from the hip, but: Our ego is how define ourselves, which must always be separate from the underlying reality (since definitions, like a map, are unequal to the territory they describe). In the sense of being an idea, it is helpful if it lead us to improve our character – by wanting to act rightly, take care of ourselves, etc.
The idea of self is strongly influenced by what other people say, since definitions are a communal thing, different from immediate perception. For example, if I know something tastes good, I know it intimately, and not because I have said, “It tastes good.” But if I am unsure, inexperienced about something, I will rely much more on what I have learned, and what other people tell me.
Since our ego is not a reality, no store should be set by it. Ultimately, I think, we strive for a direct apprehension of reality such that its own beauty is what motivates us, and not our ideas about it: “… honor us with the love of Thine Essence, that we may be freed from turning toward ourselves and toward all else save Thee, and may become wholly Thine, and know only Thee, and see only Thee, and think of none save Thee.”
Thus, I do not see the ego as evil, or even particularly unhealthy, but rather a first way of starting to understand our nature: a thing we will naturally begin to part with in the course of spiritual education, as long as we do not fall in love with it.