Dear Michael HR,
the rooms on a straight line... this happened, i believe in the 1940s (after the war), when the palace was partially restored in order to become a home to A.S.Pushkin Museum. The later was moved to the Lyceum building (connected to the Katharine Palace) in the 50s, unless i am mistaken. Alexander Palace, in turn, was handed over to the military then.
Hence the positioning of the doors - straight line - the idea was, to make it look very 1820-1830 - ish, as it was common in Pushkin's lifetime. It does look, however, as the original XVIII-XIXth centuries layout. i am guessing that was the intention of the 1940s partial remodeling.