I believe that most people hoping to do independent academic research vastly underestimate both the amount of prior work done in their field of interest, and the advantages of working with other very smart and knowledgeable people. Note that it isn't just about working with other people, but with other very smart people. That is, there is a difference between "working at a university / research institute" and "working at a top university / research institute". (For instance, if you want to do AI research in the U.S., you probably want to be at MIT, Princeton, Carnegie Mellon, Stanford, CalTech, or UC Berkeley. I don't know about other countries.)

Unfortunately, my general impression is that most people on LessWrong are mostly unaware of the progress made in statistical machine learning (presumably the brand of AI that most LWers care about) and cognitive science in the last 20 years (I mention these two fields because I assume they are the most popular on LW, and also because I know the most about them). And I'm not talking about impressive-looking results that dodge around the real issues, I'm talking about fundamental progress towards resolving the key problems in artificial intelligence. Anyone planning to do AI research should probably at least understand these first, and what the remaining obstacles are.

You aren't going to understand this without doing a lot of reading, and by the time you've done that reading, you'll probably have identified a research group whose work clearly reflects your personal research goals. At this point it seems like the obvious next step is to apply to work with that group as a graduate student / post doc. This circumvents the problem of having to work on research you aren't interested in. As for other annoyances, while teaching can potentially be a time-sink, the rest of "wasted" time seems to be about publishing your work; I really find it hard to justify not publishing your work, since (a) other people need to know about it, and (b) writing up your results formally oftentimes leads to a noticeably deeper understanding than otherwise. Of course, you can waste time trying to make your results look better than they are, but this certainly isn't a requirement and has obvious ethical issues.

EDIT: There is the eventual problem that senior professors spend more and more of their time on administrative work / providing guidance to their lab, rather than doing research themselves. But this isn't going to be an issue until you get tenure, which is, if you do a post-doc, something like 10-15 years out from starting graduate school.

After several years as a post-doc I am facing a similar choice.

If I understand correctly you have no research experience so far. I'd strongly suggest completing a doctorate because:

• you can use that time to network and establish a publication record
• most advisors will allow you as much freedom as you can handle, particularly if you can obtain a scholarship so you are not sucking their grant money. Choose your advisor carefully.
• you may well get financial support that allows you to work full time on your research for at least 4 years with minimal accountability
• if you want, you can practice teaching and grant applications to taste how onerous they would really be
• once you have a doctorate and some publications, it probably won't be hard to persuade a professor to offer you an honorary (unpaid) position which gives you an institutional affiliation, library access, and maybe even a desk. Then you can go ahead with freelancing, without most of the disadvantages you cite.

You may also be able to continue as a post-doc with almost the same freedom. I have done this for 5 years. It cannot last forever, though, and the longer you go on, the more people will expect you to devote yourself to grant applications, teaching and management. That is why I'm quitting.

I'm putting the finishing touches on a future Less Wrong post about the overwhelming desirability of casually working in Australia for 1-2 years vs "whatever you were planning on doing instead". It's designed for intelligent people who want to earn more money, have more free time, and have a better life than they would realistically be able to get in the US or any other 1st world nation without a six-figure, part-time career... something which doesn't exist. My world saving article was actually just a prelim for this.

Consider taking a job as a database/web developer at a university department. This gets you around journal paywalls, and is a low-stress job (assuming you have or can obtain above-average coding skills) that leaves you plenty of time to do your research. (My wife has such a job.) I'm not familiar with freelance journalism at all, but I'd still guess that going the software development route is lower risk.

Some comments on your list of advantages/disadvantages:

• Harder to network effectively. - I guess this depends on what kind of research you want to do. For the areas I've been interested in, networking does not seem to matter much (unless you count participating in online forums as networking :).
• Journals might be biased against freelance researchers. - I publish my results online, informally, and somehow they've usually found an interested audience. Also, the journals I'm familiar with require anonymous submissions. Is this not universal?
• Harder to combat akrasia. - Actually, might be easier.

A couple other advantages of the non-traditional path:

• If you get bored you can switch topics easily.
• I think it's crazy to base one's income on making research progress. How do you stay objective when you depend on your ideas being accepted as correct for food and shelter? Also, you'd be forced to pick research goals that have high probability of success (so you can publish and keep your job) instead of high expected benefit for humanity (or for your intellectual interests).