One Off Dramas, Sky Arts' Playhouse Presents and A Challenge to Terrestrial Channels

Sky Arts have recently broadcast the first 2 episodes of their "Playhouse Presents" series.  In case its managed to escape you, this series is made up of 10 short one-off dramas, not longer than half an hour.  Each tells a completely different story and star the cream of the British acting crop, including David Tennant, Sheila Hancock, Olivia Williams and Russell Tovey to name but a few. The first two stories have been of a high standard, both having their own unique styles, narratively and visually.  It has been a while since a broadcaster has had the bravery to commission one off programming in this nature and Sky Arts should be commended for doing so.
The last programme I can think of that comes close is perhaps the fantastic Jimmy McGovern's award winning "The Street".  This was slightly different, however, in that there was some minor overlap of characters in each story, but proved that critics and audiences alike enjoy seeing drama that isn't necessarily about cliffhangers or catching every episode to follow the narrative.  Which begs the question, why aren't there more short (i.e. an hour or less) dramas on television?
Perhaps the money men are worried that they may not be able to sell the series on to the other english speaking networks across the world?  Or because of how expensive it is to make with purse strings tightening?  If that is the case, then surely it is better to invest money in storytellers and actors that can create a piece of drama that can be sold abroad, instead of reality shows and quiz shows?  It saddens me to see the amount of mediocre series imported from America on our television screens.  Surely it would be more profitable to make our own series, which can then be sold around the world?  It seems to all come down to risk vs reward.
The other problem with less of these short one-off dramas in modern television schedules is that it leaves a small hole in the nurturing of talent.  The BBC's "Play for Today" helped many playwrights make the step between the stage and screen, many of whom went on to work on some of our most loved television programmes.  Not to mention the amount of young actors that made their first television appearances as part of the show, such as Kenneth Brannagh.
In 2006, the BBC announced it would be looking into a series called "The Evening Play", although nothing has come of this.  Kevin Spacey spoke out in 2008, saying he would like to see something like "Play for Today" return.
Sky Arts may be beginning that trend.  The Gauntlet has been laid down.  Its up to the terrestrial channels to follow suit.