Ok, I know about the circumstances regarding the making of Thief 2, that LGS was in trouble/under pressure and that a Gold edition was planned...but then LGS was closed.

Still, this doesn´t make "Casing the Joint" better.

Designwise I can´t complain - I like the big mansion, and in Masks we can even see more of it and have more freedom.

But this mission just feels unnecessary in so many ways.

The forced ghosting is a bit of a nuisance. Ok, I can handle it now, but I don´t see much reasons for it.

Then, in the story this mission seems questionable overall. I mean, Garrett never did routing before. So why now? It´s not that the security systems are that hard.
Then, wouldn´t it raise more suspicion if someone broke in and stole most to all valuables here? If I were Gervaisius, I would rather think twice about putting other valuables here and the important artifacts entrusted to me by the Mechanists if there was a big robbery going on before.

Casing just adds to the hamfisted way the endgame of Thief 2 feels.