This is interesting, because I think I see this exactly the opposite way.
When I look at the Forward Party's page, I see a bunch of really boring "good government" stuff, like RCV, open primaries, and things like "fact-based governance" and "effective and modern government." There's a certain type of person who gets motivated to vote over things like term limits and redistricting reform -- that type of person was one of the half dozen folks who voted for Paul Tsongas, and their solution to everything is campaign finance reform. They represent about 5% of the electorate, and the entire political establishment is united against them because all of these things are a direct threat to incumbency. It seems to me that it's basically impossible to get a new party off the ground on issues like this.
The other problem that third parties sometimes run into is trying too hard to be "centrist." The Reform Party was kind of like that at one point. Again, you can't motivate people to engage in party-building on the back of "we should run government somewhat more efficiently." You need something that inspires.
My knowledge of the history here might be mistaken, but I was always under the impression that the Republican party started off as basically a single-issue party focused on abolitionism. I'm sure they campaigned on other stuff too, but that was their one, big, motivating idea. It got them off the ground and into the White House fairly quickly.
Given how rotten the GOP has become and how the Democrats are on a similar trajectory, it feels like there's a real opportunity for a political realignment that could include a new party replacing one of the current two. But that new party needs to give people a reason to support it. Something like UBI would represent a transformational change to how our society is set up. It might be a bad idea (I'd probably support it), but at least it has the potential to get people excited. It's also a welcome change of pace from the same stupid culture war issues and the familiar debate over whether income taxes should be marginally higher or marginally lower. It's different in a way that lets a new party differentiate itself from the other two -- neither the Republicans nor Democrats would ever invest any political resources in something like this.