You should add lack of business and executive experience, at the least. Also, AFAIK, he has not done military service, which will be another putoff for some.
There are lots of things that will "put off some."
But there's no reason to believe that "business and executive experience" or "military service" effect support to any meaningful degree. In the last 30 years we've had one (1) President with legitimate military experience (Pappy Bush). In the last century-plus, we've only had two Presidents for whom military experience was a significant element of their prestige.
Likewise, we've not elected someone with 'business experience' - and no one in the primary or the general, Romney aside, is a captain of industry.
Executive experience - people may like state execs, but there's not conclusive evidence that gubernatorial experience weighs in the public mind more than being a sitting Senator. And in all likelihood, Obama wouldn't be facing a former governor in the general.
You're proceeding from a lot of strange assumptions.
Finally, there are independents that just don't like overly liberal candidates.
Um, yeah, except that Obama isn't positioned as "overly liberal" - hence his stance on gun control (the most 'liberal' position taken) is what I find as potentially objectionable to moderates and crossovers.
While I know that the APS hive mind thinks he's a Stalinist, Obama's rating among self-described moderates and conservatives in the rest of the world is pretty bloody good. Certainly far superior to Hillary.