I get ya. I actually started up a few tk's on my own after doing research on them again. And I'm not a scammer/malware abuser, :p.
True, that's another good reason to use them, . Also, the benefit of .com over .tk is solely about SEO. Other than that there are no differences. And that only matters because .tk is a country-based domain and .com is universal.
Actually, a lot of registrars give free privacy. The problem is if you're running an actual business (or really anything where you want authority) you need to leave it public as transparency (stores, authority blogs, etc.).