I'm not sure that I understand the problem with making a boundary between the sanctuary from the nave; that is still done, usually with a step or other transition.  This is not to set the clergy (and, now-a-days, other ministers) apart but to recognize that it is to be a place set apart for the sacrifice.  Note the "good" example that (Mr. / Dr.) DeSanctis consulted on (http://www.stmichaelcommunity.org/).  The sanctuary is set apart by stairs and a different type of flooring, with the altar elevated even above the lectern.
If altar rails aren't in keeping with the architectural style, however, let it go.  While I don't like playing "Where's Jesus" when I enter a church nor care to see the band up front, some may; I just avoid churches that, for me, will be a distraction.
I do appreciate the admission that "there has been bad modernist design through the past few decades..." [rightly] "...castigated by young clerical restorationists."  I think that may be an understatement.