Overall, the general theme of "populism" whether or not it comes from Republican or Democratic talking points, is one of pitting "the people" or "the masses" against some hypothetical "elites".
Overall, beyond merely being used as a tool by politicians to manipulate naive people's emotions, I can't think of much good about populism, my rationale:
1. Populism is associated with anarchy, mob rule, and totalitarianism, rather than any actual effective Democratic society - It has more in common with the rhetoric used in the French Revolution than the American Revolution; likewise both fascist and Soviet regimes employed populist rhetoric to manipulate "the masses".
2. Populism on the whole is associated with low manners, morals, and character - basically it's a reversal of the natural order of things, as it attempts to "glorify" the mediocre, less creative, less moral individuals of society while at the same time demonizing the more creative, successful, and virtuous as "elites". This seems to be true regardless of what specific incarnation it takes - whether racial or sexual identity politics, the antics of the Occupy Wall Street movement, or the demonetization of higher and more creative professions such as arts, music, theology, in favor of simpler and more utilitarian ones which better service the material interests of the state or regime, as we see in many authoritarian states such as the Soviet Union and North Korea.
In reality I see 'populism' the way it's employed as having very little in common with America's Founders, or with Greek democratic systems which America's government was inspired by - essentially the Founders were meritocratic; they believed every man had the potential to be great, and should be judged on his own character and worth rather than his position of birth.
However, they didn't blindly idolize the "masses" or "common man" like the anarchist and radicals of the French Revolution did, or as in the rhetoric which the Soviets and Maoists employed.
The type of "common man" the Founders admired was a virtuous, self-made man, while at the same time the Founders were quite distrustful of the "masses" as well as direct democracy, as they feared it would lead to mob rule, and didn't believe that mobs were fit to self-govern.
I believe part if this is that they were wise to understand that any man with no higher sense of purpose or value in life but his mere materialistic needs could every truly be 'free' to begin with, or anything other than a slave, since he lives every day as a slave to his own materialistic vices. Likewise in the Athenian Democracy, only those who demonstrated some basic meritorious requirements were allowed to be citizens or participate in government.
So on the whole, it's hard for me too see much good in "populism" as a political ideology, and I see it more as a tool by con men used to prey on the emotions of the masses, and recruit mediocre individuals without a strong sense of self-identity into their "movements".
The term and its definition you are using come from an earlier time when - as you say- "The type of "common man" the Founders admired was a virtuous, self-made man". The problem we face today is that our form of government does not consider these attributes when selecting leaders.
Consider the reality that our government is controlled by special interest. (and I would welcome anyone who could argue it is not the reality) Special interest groups and the lobbyist that influence our legislators are bought and paid for with big money, something our unorganized populist can not compete against with petitions and letter writing and phone calls.
It is only through a raising up of 'Populism' that the common man's interests (and common sense) can be brought to bear and overcome these special interests, which are most often focused on profits over people, profits over the environment and profits over our collective future.
I would argue that the US has always been controlled by special interests.
From many of the sponsors of the revolutionaries having strong ties to illicit trade, to the vote only going to land owning males and the compromises made to the slave states and so forth and so on.
support for the concerns of ordinary people.
the quality of appealing to or being aimed at ordinary people
Like most other things, its application in any given situation can be good or bad. But support for the concerns of ordinary people is not inherently bad.
I am become memes, the destroyer of sam.
It's just like him to leave before I can show him the fruits of my labor.