What has happened to the kind of discomfort I felt as young person when I saw gross ostentation? The bright red Rolls Royce is gross ostentation. It screams, "I'm rich, richer than you."
I think that two things have happened to change American attitudes towards gross ostentation.* First is the rapid growth of meritocratic wealth. 
We have about two million people who inherited their wealth, the traditionally wealthy who avoid ostentation because the society around them justly views their wealth as undeserved. Most people in the category of inherited wealth are donating and squandering their wealth, since few heirs have the ability to earn it.
Meritocratic wealth is earned by skill, talent, effort and a little luck. There are roughly two million people in this category, also. This group wouldn't generate much envy or opprobrium if they were ostentatious, but the public wouldn't know merit from inheritance. So this group follows in the path of inherited wealth and avoids ostentation. The meritocratic wealthy hide their wealth in gated communities and far away from everyone in the mountains around Aspen or deep in the glitz of Beverly Hills. Some members of the new meritocracy are artists and athletes, showing that this class is ethnically mixed and unlike the traditional, inherited group.
The second change over the past decades has been the arrival of big money winnings in the state lotteries since the mid-1970s, the popularization of Las Vegas, and television shows that give $ millions to contestants. This is the lucky money group.
It is the arrival of this group of chance winners that has changed the dynamics of ostentation. Few people bear a grudge against lucky money, since anyone could be lucky. My guess is that the class of lucky money people is under 100,000.
I think the consequence of these two social changes in the past several decades, merit and luck, is the decline in hostility to ostentation. The arrival of meritocratic money diminished the moral basis for hostility to ostentation. The explosion of lucky money eliminated the antagonism to ostentation and almost created a welcome mat for gross ostentation.
After all, I think that when someone sees a red Rolls they think: Lottery.
Part of my point is made with a late 1950s joke I heard nearly fifty years ago: A black man, a pimp, goes into a Cadillac dealership and sits in the driver's seat of a pink convertible. He lights up a cigar, under his broad-brimmed purple hat. The salesman approaches and asks, "What do ya think?" "I'd take it, 'cept people might think I'm a Jew."
*Such change in attitude has not happened in Japan, India nor Israel.