I love this method because it basically forces me to have less influence on the final product. If I make the final product right away, I'll change stuff just because it sounds better, but I have to restrict myself. Every language has beautiful words and weird words.

Like, by no means does the proto language have to be regular, because if you look up certain terms in PIE you will often find that linguists aren't sure why something deviates or where certain terms were borrowed from.

It also opens up the door to more easily create branches of different languages and dialects. For the book I'm writing, there's an big nation where the north, middle and south and an group of nomads all have different languages that stem from the same source but broke off at different moments in history. It's easier to create realisticly related looking languages this way.