I do agree with a lot of both of your points. You definitely can teach yourself music; I'm self-trained myself. I play about a dozen instruments (to varying degrees of proficency!) as well as electronic composition. All you really need is the time and dedication, and a LOT of both.
If you want to make music, then, yeah, there's nothing stopping you. If you want to be a composer, however, you need to know theory. You don't need formal education, but you do need education. You need to know counterpoint and harmony, you need to know scales and modes. You need to know how all the instruments you want to compose for work (though you don't need to know how to play them), otherwise when you get to the level where you are handing off sheet music, it won't be playable by a live musician. All that and composing for film is an entirely different beast than just being a good musician, or a good composer. And, like anything in life, you never ever stop learning. There's always more to know.
But all that aside, you can throw together music that you like without having that knowledge. FL has come a long way (I think part of the snobbery against it has to do with people who tried the first few versions. Acid gets the same thing; they're both now capable of multitrack audio and MIDI/VST integration, but there was a time when neither of them were). I remember Orion being a lot of fun to play with, and pretty "beginner friendly." Each VSTi has it's own loop/piano roll to build pattern based sequences with. And if you want to go old-school techno/acid, Rebirth is free these days:
http://www.rebirthmuseum.com/ (note: that's a very specific use synth and not as flexible as a full-fledged DAW). Oh, and
http://www.kvraudio.com is an absolutely essential resource for plug-in effects and instruments, lots of which are free.
Anyway, how deep you want to go really depends on how far you want to get. There is absolutely nothing wrong with just wanting to do music for fun, and not being serious about it. There's nothing wrong with being serious about it, but teaching yourself. That said, I've been a DIY guy since I first picked up a guitar, but if I had to do it all over again, I would have gone to school for composition. You can't know too much!