I would have signed that letter complaining about the questions asked by ABC's Gibson and Stephanopolous if someone had asked me to. However, they may have done Obama a favor in the end by giving him a dry run with this sort of trivial stuff, which the Republicans will surely hit him on hard in the general election (although it is my understanding that John McCain does not wear flag lapel pins much more than Obama does, although clearly he can get away with that better than Obama).
No, the much bigger problem with the debate was Stephanopolous asserting (in contrast with the US NIE finding unanimously agreed to by all 18 US intel agencies) that Iran is pursuing nuclear weapons and asking the Dem candidates what they would do about it. Neither called him on what garbage this assertion is, especially in light of the fatwa against nuclear weaons by Vilayat-el-faqih and Commander-in-Chief of the Iranian military, Ayatollah Ali Khamene'i. Instead they both declared how much they opposed this by Iran and supported defending Israel on the matter, although Hillary went much further than Obama, proposing a defense shield over all of the Middle East, something beyond anything advocated by either Bush or McCain. I observe that about the only media people to note the extreme nature of this declaration were Rachel Maddow and Patrick Buchanan on Olberman's show. This is far more appalling and serious than all the dreck posed in the first 45 minutes.