There's some merit to what you say. We used these methods for years to take the chill off during the shoulder seasons, and got along alright.
That said, now having sailed for a few years with the real cabin heater -- I would NEVER go back. The difference in comfort level so is so stark that it's really beyond comparison. It's almost like the difference between sleeping in a tent and staying in a hotel (slight exaggeration). Our early and late season forays are much more enjoyable now. Of all the "comfort" investments we've made, that cabin heater was some of the best spent money.
Fuel choice is always debatable. As I've said in other threads, if we were long-term voyagers/live-aboards, I'd certainly give serious thought to the Webasto/Espar forced hot air diesel heaters. I've experienced those and they are wonderful units. But for our kind of sailing it's more difficult to justify that expense -- something like 10-15 times as costly.
Wood is tricky for a lot of reasons, but if that's what you prefer so be it. However, I would not recommend the Dickinson Newport wood heater for serious cabin heating, based on my conversation with them. Instead, if I was going with wood, I'd look at something more along these lines:
Wouldn't it be cool to have one of those in an old wooden schooner?