Lagging in Transfiguration?

[Cindy C.]

No: HPFGUIDX 28559

I was listening to PoA (yes, again!), and it occurred to me that our 
trio and their classmates don't know a great deal of useful 
transfiguration, even though they are more than half way through 
their wizarding training.  Indeed, Harry got through all three tasks 
in GoF without a single bit of transfiguration.  I don't have my 
books with me right now, but I think the most complex thing they have 
done is change a tea kettle into a turtle, and only Hermione seems to 
have done it correctly.

It seems to me that transfiguration is a Huge Big Deal in the 
wizarding world.  We see powerful wizards conjur things out of thin 
air (which I assume is transfiguration), such as Sirius conjuring 
manacles and Dumbledore conjuring chairs.  Transfiguration is 
necessary to become an animagus, of course, and I assume it plays a 
role in Apparating.  

Are the students far behind in Transfiguration, and if so, why?

Cindy (who hopes the students are good at multi-tasking so that they 
can get up to scratch on magic while fending off dark wizards at the 
same time)