While yes the original dressing used on a Reuben is Russian, you must realize that almost all places use 1000 island now and there is very minimal differences between the two. Most restaurants would need to make their dressing homemade if they wanted to use Russian, and I can tell you from many years experience that it makes much more sense to use 1000 than make homemade Russian due to labor and shelf life issues. I've had equally really good Reubens with 1000 and Russian on it. The actual definition of Reuben sandwich lists Russian or 1000 island dressing.
While that may be your opinion, I respectfully must disagree about the minimal difference. Russian and 1000 Island dressings are WORLDS apart...the Russian dressing simply makes the sandwich.
Your opinion is respected and noted, but I must disagree.