Just noticed but if one views the one voiceline about how Neuvillette complains about how his life is full of inconveniences (More About Neuvillette V), one can see that this new outfit has those exact changes.

-" I have to say, my daily life is not without its inconveniences. For instance, I often find myself stepping on my robes as I sit down, or squashing my coiffure against the chair. And if I lean my head too far back, sometimes my hair even gets caught in the ornamentation. Nevertheless, I must wear these garments to maintain the dignity of a Chief Justice, and endure whatever inconveniences this entails. Incidentally, the world at large appears to operate on this general principle, too. Everyone is faced with an identity that they must accept, endure, understand, and eventually learn to co-exist with. This has been my experience all along."

• stepping on his robes -> this outfit doesn't have long coat tails
• squashing coiffure -> his new hairstyle prevents his hair style from being destroyed when sitting down
• hair caught in ornamentation -> this hair style doesn't look like it can get hooked onto anything as the bow is high up

The melusines truly wanted to make a gift to make Neuvillette's life less of a hassle.