Street art, anyone?

I had a bit of a streetart fixation a while back, and this video brought the memories flooding back:
http://uk.youtube.com/watch?v=uuGaqLT-gO4&feature=rec-fresh
(I suppose it's not really street art per se, with the intended artwork being the resultant video, but it's still awesome and semi-relevant. Then again, who am I to say what is and isn't street art?)

I loved the idea of using public areas as space for art - presenting art where it was least anticipated, and making it accessible to a wider audience who otherwise mightn't interact with it... like some insidious program of indoctrination to make all the world art appreciators*. I also fell in love with the anonymity of it (with the pieces not easily being attributed to any one person, it seems to run less of a risk of being seen as for the sake of ego, and the concept of faceless communication just makes me insanely happy), the idea of proving that not all markmaking in public spaces is necessarily malicious and aesthetically displeasing (as is such in the case of tagging) and, to be honest, the slightly subversive undertones of making art where it supposedly shouldn't be.

However, after further thought I realised a few drawbacks. For street art to be noticed by any large number of people, it would have to draw attention to itself by being large/bold/colourful/whatever, as people wouldn't generally anticipate finding art outside of a gallery, and thus street artists would be somewhat limited in terms of style (though there's enormous room for variation within those limitations. (God I'm contradicting myself left right and centre.)) Then again, that is supposing that the artist would want to draw attention to their work... but what can an artwork do if no-one knows it's there?
Also, would proper consideration be given to concepts behind street art (presuming the artist has something specific to convey)? How many people passing by something on a train station are going to stop and stand and think about it? I suppose the same could be said for works in an art gallery, but at least if you're in an environment surrounded by things that you're told are art, you're going to at least attempt to think about them. (Incidentally, do you think if things like the works in Experimenta Playground were placed in somewhere like an arcade or a cinema anyone would extract the same meaning from them?)

I guess the latter point could be overcome by sticking with one particular visual language - one that is bold and straight to the point (a lot of work, like that of Banksy's, is quite unsubtle) - but I just really dislike the idea of restrictions when it comes to artmaking.

Actually, that presumes that street art is only the "imma paint/draw/attach an artwork on/to this wall/seat/etc now, and I don't have council approval!", rather than other forms such as the subtle alteration of preixisting things on the street, or larger planned/approved works such as "Maria Kozic is Bitch", a billboard by Maria Kozic (...I'm not 100% sure if this was actually placed on a public billboard because I am going mad).

Um. I've kind of forgotten what I was talking about so I might stop.

*Okay, I exaggerate. But I really would like something like that to happen one day. Nothing coercive, of course.