Ah, the ol' "Stupid Dark Tan Imps" conversation. I had a revelation on this the other day. I was playing the best Star Wars game evar, Jedi Knight II: Jedi Outcast, when I discovered something. In the game, there are black-uniformed officers, dark bley-uniformed officers, and...... dark tan officers. *Gasp* Now, I'm not saying Lego is using this game to justify their production of dark tan officers, but there are a number of precedents for producing dark tan officers:
http://d1vnh8mbrp67em.cloudfront.net/screenshot/image/8/b5/244278/00267812.jpg
http://vignette2.wikia.nocookie.net/starwars/images/7/72/UnidentifiedImperialGeneral.png/revision/latest?cb=20100810180725
http://cdn.wikimg.net/strategywiki/images/4/43/SWJKDF2_enemy_Officer.png
http://vignette2.wikia.nocookie.net/starwars/images/d/d6/AdmiralOzzel-bodyshot.png/revision/latest?cb=20141113205943
http://www.jollyandy.com/wedding/wp-content/uploads/2013/12/GeneralVeers.jpg
https://s-media-cache-ak0.pinimg.com/originals/e1/eb/e0/e1ebe03e89c073dd0ee38175e1048685.jpg
Take this as you will. I know there are some die-hard bley Imperial officer people on here. I can only speak for myself, but I certainly appreciate some variation in the uniforms. I'm sure we'll get some regular uniforms with the RO sets or possibly the UCS DS.
In the end, I think there's a real-life parallel between Imperial officer uniforms and WWII German uniforms:
I see tan, gray, and olive. Just like.... *gasp* the Imperials. Food for thought.