you are right, there is a loss of experience and that is on both sides of the world...pilots and controllers.
AS a controller you have the right to ask anything you want. AS a pilot I have the right to say no.
AND if things conflict, I declare an emergency and tell you to go to hell. BUT that is way too much paperwork! ;-)
OF course we both want to avoid this. knowledge of capabilities is vital.
I have been told by a controller that I should increase my rate of climb to 3,500 fpm. I've told them it was impossible...and they said: we have a book here that says you can, so do it!
I told them that on a HOT DAY with a full load of fuel and passengers I was lucky to give him 1500fpm.
On a cold day with a half full airplane, I might have been able to help.
And as to getting down...10,000 feet, 30 miles out is normal...
if you forget to clear me for an approach and I am 5 miles out at 3000', I will shake up everyone in back if I have to get down that fast...so avoid the request for an "orbit" by being ahead of the game.
so think ahead...the glideslope is the perfect reference...and you are not supposed to vector us on to the approach ABOVE the glideslope...some autopilots have to be forced to capture from above and not below.
I learned this stuff along time ago and believe me, I will be jumping up and down asking for lower...but the new guys might not