Why has the orbit of Venus such a low eccentricity?
It has a low eccentricity, but there may not be a particular reason.



Image by Kheider on wikipeda using Gravity Simulator by Trevor Dunn

In a simulation of the solar system, both Earth and Venus had orbital eccentricities that were much below those of Mars and Mercury (note the two axes. Mars and Mercury are on a scale that is 10 times bigger). But in 25000 years, Earth will actually have a smaller eccentricity, and 20000 years ago Venus's eccentricity was much larger.

So there may not need to be a special explanation for this. Planetary eccentricities do change over 1000s of years due mostly to perturbation of other planets.