I do this for all my character as a dm and I think it is gear to add that visual layer for player who like it.
Before it would be image search and take what a er is closest to the character. I think wonky Ai pictures, despite all their downfall, are a real improvement in this usecase .
Plus it's not like it's commercial usage, nor would you have hired artists to illustrate all your characters for a session like that. It's one of the few ethical usages of AI, imo.