Orchestras and Composers

I was reading a blog by Ilkka Talvi, Of Music and Men, in which she was talking about the lack of modern day composers, for orchestral pieces, which have the basic requirements of memorable melodies, engaging rhythm and pleasant harmony.
In a lot of ways this is true, too often contemporary pieces are heard that don't fulfil these elements, and leave the audience somewhat bemused.
It isn't as simple as that though. I feel orchestras have to take some responsibility as there is music out there that just isn't being heard.
I understand their problem, they need to perform pieces that will guarantee an audiences. However, some risks should be taken to move the whole process on. They could always schedule a well known piece alongside a new composer in the hopes that they will attract their usual audience.
As I've said before on this blog Robin has composed many pieces for guitar and orchestra, one of which has been performed with excellent reviews, (by the newspapers, audience and orchestra themselves), and yet it's difficult to get another performance. Crazy.
I'm sure he's not the only one that has this problem.
FOOTNOTE:
Having published this blog mid-afternoon I happened to be listening to BBC Radio 4 at tea time only to find they were discussing this very topic. That's excellent news and hopefully we will see the tide change....