We might hang a satellite in orbit in a perfectly circular orbit but even if the earth and that satellite were the only objects in the universe, the surface of the earth is not cue-ball smooth, and those irregularities cause differences in gravitational pull, which, over time, would cause the orbit to become eccentric. So in every case, eccentricity is inevitable.
You could use thrusters to keep it (sort of) circular but you'd have to burn fuel to do it, and refuelling satellites is an expensive proposition, so they tend to let grabity have its way.
Pluto's orbit is so eccentric, it sometimes is closer to the sun than Nepture is.