Stepping back in time for a moment, the traditional grille design was not a styling problem until around 1950 when post-war designs were becoming the rule. From the early 1900s through most of the 1930s, luxury cars were conservatively styled, featuring separate elements such as hoods, front and rear fenders, headlamps, and so forth. The Rolls grille was just another example of one of those elements, its distinctiveness aside. English automobile fashions being more conservative than in America or on the Continent, Roll-Royce cars continued their pre- World War 2 appearance with only minor concessions to "envelope bodies," "pontoon fenders," horizontal grilles and other design features that became near-universal in the early postwar years.
Sooner or later, Rolls-Royce had to begin conforming to fashion, and its Silver Cloud (1955-1966) appeared bearing many concessions to modern design. I wrote about it here. What I failed to mention was that it was styled by John Blatchley (1913-2008), who got his start with coachbuilder J Gurney Nutting and moved on to Rolls-Royce in 1940, where he remained until his 1969 retirement.
The Silver Cloud was succeeded by Blatchley's Silver Shadow, produced 1965-1980 (Wikipedia link here). It marked Roll-Royce's complete transition to modern design, even to the extent of having unit-body construction. And it sold well enough for a car in its price range.
If the Silver Shadow can be considered something of a sales success (provided an average of around 2,000 sales per year counts as success), its styling is problematical. Squared-off "three box" styling was fashionable roughly during the period 1960-1985, and the Shadow's design fit right in. Its appearance was dignified, as would be expected of a Rolls. However, to me, Silver Shadows simply do not look impressive -- something the earlier Silver Cloud did.
Blatchley was able to retain the traditional grille and hood form by simply making the grille shorter in order to conform to the rest of the Silver Cloud body. Later Rolls designs continued the traditional grille until BMW acquired the firm and launched new bodies where the grille was blended into the more aerodynamically efficient shape.