The argument about "trying to be taken seriously" has been going around and around forever. Todd Gitlin has made an entire career out of it. If you look at old photos of the early gay 60s rights movement, they deliberately looked conservative and establishment in an attempt to be taken seriously. A far cry from the pride parades of the past 20 years, but who would argue that things are worse for gay people now (and yeah, that Onion headline about pride parades setting gay rights back is funny, it's but not really true)?
I did a lot of activism around public space in NYC in the 90s, and the big knock on "the left" at that point was that it was humorless and self-serious (lots of vegan/New Age/anarchist cracks). So we would pull off goofy street theater stunts and in the space of a few years the knock was that WTO/IMF meetings were like Dead shows and the global justice movement wasn't "serious." Both critiques had some basis in fact, but ultimately media perception hardly makes a difference. For whatever reason (corporate ownership, the fact that most movements don't turn out to be newsworthy, the general elitist bias of the Ivy League types who make up the media) most movements aren't taken very seriously until after they achieve something. And when they do achieve anything, it's usually because the stakes are high enough for people to put themselves at risk, like in the Arab Spring movements (or the anti-nuclear, anti-apartheid, or gay rights movements -- three successful campaigns that took place in the Reagan era). If things get so bad that American young people are really out of options, that encampment is just going to get bigger. If not, it won't. In the former case, it will be taken seriously, even if it's full of hippies wearing V masks. If it's the latter, it probably won't, no matter who shows up.
As far as the Tea Party goes, it was a genuine grassroots movement, but it was a fraction of the size of the anti-Iraq-war protests in 2003. But unlike the antiwar protests, it was kept alive by constant media attention (from the NYT and WaPo as well as Fox and CNBC) and large sums of money from people like the Koch brothers. The antiwar protests were briefly covered, then ignored, and most people just went back to their lives. I did too. People are busy, and there is no draft.