Of course it is a gil sink.. And new content.... That is how this game works.
Most things you buy in this game are worth less after you buy than before. Including every outfit you buy, every weapon, crafting item, etc.
As for "pretty package"... Well sure... Minions have no value, and many are a gil sink. They certainly serve no purpose whatsoever, whereas housing does actually have some benefits.
But anyway, as per minions, the pretty package IS what people pay for. Or completionist credit. It doesn't have to have any real return value.
And housing is certainly more worthwhile over the long term than minions, or gear that will be obsoleted next path/dungeon you run.
