Ken,

The purpose is that your wife likes it! What else do you need to
know???

It's a little hard to tell from the photo, is it flush with the floor
or does it raise the toilet some? If the latter someone might have
done it in part to raise the level. If flush, maybe that was just
someone's idea of a high class touch, or they wanted an extra-stable
base for the toilet.

It will not be a big deal for a professional tiler to tile around it.
They might recommend putting some sort of tile border around it.

-- H