Its to do with comparisons and your ears. The lower strings have lower harmonics and if you start from the bottom to the top with the other strings tuned when you get to the e string it will be easier to tell if the string is in tune.
Why are violins tuned the way they are?
In the beginning, your violin teacher will help you tune your instrument - and is happy to do so because tuning is crucial to developing a good ear and the muscle memory required to play the notes accurately. At some point, though, violin students need to learn to tune their instrument on their own.
What frequency should I tune my violin to?
Violin strings are typically tuned by setting the A string to 440 Hz. It's a scientific metric applied to a tool of art, which in itself might seem odd.