Normally I would sort of dismiss this as Lessig is not viewed by myself or pretty much anyone else as a serious candidate for the presidency; his place at the debate, quite frankly, would be a major distraction from the real issues and he would be the equivalent of Jimmy McMillan proclaiming the "rent is too damn high." However, Lessig has validity when he points out that he would likely be in the debate if he had been included in polls, which are independent and therefore he has no real way of influencing whether he is an option in them. This is because the bar to get into a CNN debate is exceedingly low; all a candidate needs to do is achieve 1% in three national polls in the last three months. Considering that candidates that don't actually exist could reach 1% in a national poll if you asked their name enough times, it's more than likely that people would pick Lessig (or for that matter, almost anyone else) and get him into the debate. This poses a problem not just in fairness for Lessig, but also to the reality that the bar to get into the debates is too low. Looking at the candidates that did make it into the debates, Lincoln Chafee, Jim Webb, and Martin O'Malley have less than 1% aggregate polling numbers both nationally and in early primary states like Iowa, New Hampshire, and South Carolina. None of these candidates, according to Real Clear Politics, were able to reach even 1% as their average in these major polls, but because polling generally can get pretty much anyone to 1% at least a couple of times if they're included, all three will be allowed to debate.
The reality is that these men are being included, though, not because they have reached an arbitrary number in the polls, but because the powers that be are including them because they are former senators and governors. They did, in fact, reach a major office which Lessig has not, resulting in them being "taken seriously." Again, normally I would be siding against Lessig's argument here because the reality is that a former governor would have the executive experience to be able to run a country (or at least would in theory) and a former senator would have the national policy experience necessary for such a position (again, at least in theory), certainly more so than your average Harvard professor. However, this argument taken in conjunction with the GOP race runs into some inconsistencies. In the GOP race, it's clear that Carly Fiorina, Donald Trump, and Ben Carson would need to be in the next Republican debate based on their positions in the polls, as all three are doing quite well nationally. However, none of them have experience in high-elected office, but other candidates like George Pataki or Lindsey Graham who were included in the polls have become non-entities similar to Webb/O'Malley/Chafee. However, by the logic of the Democrats, Lessig can't achieve the level of a Fiorina or a Carson, but they would have included people on Pataki and Graham's levels because they are major former or current officeholders. It's unlikely that Lessig could achieve the sort of polling numbers that a Carly Fiorina did, but Fiorina started with numbers similar to Lessig and worked her way up through the first "junior debate."
I think this points to a larger issue to what may be a continuous problem for both parties going forward: the large fields of too many major candidates will make early debates relatively pointless, and the threshold to enter them needs to change. With seemingly little consequence involved with running for president these days (it seems to only help you gain in stature nationally, and who knows-you might win), I suspect that should a Republican win in 2016, the Democrats will have a similarly-large field in 2020 as a number of senators and governors decide "why not me?" in the face of a frontrunner gap. If a Democrat wins in 2016, I suspect a similarly-large group of Republicans will go into 2020 assuming the Democrats can't hold the Oval Office for sixteen consecutive years. All-in-all, this large group of candidates problem is not going to dissipate, and I think a better solution for the principle debates, which seem to be so crucial in shaping public opinion (just ask Carly Fiorina and Marco Rubio, not to mention Jeb Bush on the inverse), would be to require a 5% aggregate polling for entry. This would raise the bar much higher and give a chance to the candidates whom America actually wants to hear from. Admittedly it sort of spits on the "Mr. Smith" style candidacies, but let's be honest-those don't really exist anymore. I'll be generous here and say that it would be either 5% nationally or 5% in one of the three earliest primary states (IA, NH, and SC). This would mean that Fiorina, Bush, Rubio, Trump, Carson, and Cruz would all be in the next GOP debate, while Clinton, Sanders, and, if he were to run, Biden would be the Democrats debating. Admittedly that could set up an awkward moment for Sanders and Clinton (it'd be like a general election debate at that point if Biden didn't get in in the next 72 hours), but it would at least be with the candidates that people are saying they want to hear from, and allow the populace to get more substance from the candidates they are clamoring for, because quite frankly having Mike Huckabee or Chris Christie up on stage for the GOP debates at this point is a waste of time, and we should be hearing from the six candidates whom the American people actually want to hear from instead. All of this probably won't help Lawrence Lessig's quest to get to the debate stage any easier, but it would make his exclusion a lot fairer.