I'm currently reading John Mortensen's wonderful book on keyboard improvisation. (See this link here.)
In the chapter on figuration preludes he states that the progression I - II4/2 - V6/5 - I was a popular "opener" or "page one" progression for such preludes. The most famous example being of course Bach's Prelude in C Major from WTC 1, BWV 846.
But why this particular progression? In particular, I wonder about the role of II4/2 here. Not by any stretch an uncommon chord in the late Baroque, but not particularly ubiquitous either.
Of course, the goal of any opening progression should be to establish the tonality firmly, but there must be dozens of progressions that accomplish this.