Yeah, the point of all these movies is time travel is used as a metaphor/symbol for other human relationships and experiences.
In Back to the Future, time travel is an investigation of memory and the relationships between parents and children.
In the Terminator 1 and 2, time travel is about pregnancy and motherhood -- about the power and fear in reproduction, and the indirect connection it offers people to the world after they're gone.
In Looper, time travel is about decadence and hedonism, and about the effect on your life of the trade-offs that young people make in their career choices.
This is at the root of why Looper, while still a pretty good movie, is not as great a time travel movie as the others mentioned, and why reddit is full of fans of it while the rest of the world isn't -- the scope of what it's investigating is not really universal -- most people don't really confront the choice of living their 20s and 30s like high-flying rich boys with the reasonable fear that when it's over they won't have any meaningful personal relationships.
And I also found the end of the movie really unsatisfying, partly because it represents suicide so inauthentically (as a choice you make in the moment for calculated reasons, which is almost never the case), and partly because it loses track of what the main character's problem actually is.
The problem is regret. Yes, there's the issue of saving the future, but really Old Bruce Willis is grizzled and regrets the decisions of his youth and is trying to reverse them when it's impossible to do so. And then young Bruce-JGL-Willis is confronting the consequences of everything he's chosen to do, realized what he left behind and lost by choosing to live the high life, and wants to change his decision too.
But the movie takes a big thematic turn about 2/3 of the way in, it stops being about the two versions of the guy and starts being about this kid. And at this point everything would be better for everybody if the main character just didn't exist, and so he doesn't exist.
This removes all the tension and invalidates everything the movie has been about until this point -- an irresolveable combination of regret, the battle over a person's decisions and future, people trying to change. Because in the end that isn't allowed to even be important at all.
B-JGL-W isn't allowed to decide to change, really. He's never allowed to choose a different life than what he had. He's allowed to realize that he is worthless relative to other people. Which was never the question and never the point.
It certainly steps a whole ways away from its real-world analogue situation: "Well, you're a high-powered investment banker or tech ace with a great house and a great car, but you never found love and never had children and feel really alone. You're starting to realize you cause problems for the people around you and never care about the consequences or your potential obligation to them."
"YOU SHOULD KILL YOURSELF. PEOPLE WILL LOVE YOU IF YOU KILL YOURSELF," is a really unsatisfying resolution to this conundrum, especially when it isn't portrayed in as credibly deranged and sad a manner as it would really be if somebody did that in real life. It's portrayed as way too heroic -- to dodge out on your problems and just leave as if that fixes everything.
And it's not that I doubt some people see it as satisfying, but I don't like, identify with or connect with that view of art or humanity. And I think that the parts of the movie that are actually good are really inconsistent with this message (the pity and fear we feel for the guy being cut apart -- because we value life, and the scene in the diner, because we value connection, and even the Jeff Daniels scene linked to by OP, because we understand what it's like to be a bad man giving good advice), which shows that for at least some of what was gong on, they were on a better track with it.