The benefits of using Roman (and pseudo-Roman) names for one of the cultures in my campaign...

...is that I can slip in scientific names for plants and animals to amuse myself. The characters ran into an NPC named Brassica Oleracea, or example.

But in all seriousness, use of a real language as an inspiration can, if used well, help as a shorthand for understanding the culture of a group. The Aquilans are pseudo-Romans. This gives a sense of how bureaucratic they are prepared the churches to be, how trained and regimented Imperial centurions are, etc. It brings with it an ease of description that is hard to do otherwise.

You know, plus the scientific names joke thing.