You make some good points Sweet17 and I agree with all of them, I wasnt advocating that you must learn like a child just that is what happens naturally when you relax and go with the flow, formal learning is of course important without it children and adults would not get to grip with grammar,conjugation, the subjonctif tenses, punctuation or just plain spelling.
I havn't had a lesson since 2007 sadly but my learning has gone in in leaps and bounds since thanks then to those very formal lessons as I build on and use the knowledge every day, without them I would become like a few people that I know that have learned in on the cuff or pillow, they understand a,d speak well but dont have the confidence to write.
As for learnin. like a child I did an intensive course of Spanish in Quito and that is exactly how we learned (or is it learnt? still weak in english) using childrens picture cards and games etc, it was a very very powerfull way of learning and I was amazed at how much we learned in such a short space of time, mind you compared to a young child we were nothing, the other key ingredient of this course was 100% total immersion once they had your money no matter what the problem was they refused to speak to me in English at the end of a couple of weeks I thanked them for this.
The first thing I did in France was to travel to Grenoble for an intensive course with a newly qualified native teacher that i met on the great barrier reef, her style of teaching was very up to date compared to my following teacher who had only trained herself some 10-15 years before, the young girl did a lot of teaching in the child type way but reinforced with grammar, tenses etc.
I suppose I am lucky in that my life in France has been 100% immersion although I didnt consider it luck for a very long time.