The issue is quite simple.
ATC assigns a speed, aircraft complies.
So far, so good.
At some point however, the airplane does indeed have to slow down to actually land...as quite frankly, that is what we a paid to do.
So, for the ATC folks, they had better start to be more precise, if they want precise speeds.
By this, I mean, if you want say, 200 knots, and yet say nothing more about speed, clearly the pilot has a duty and responsibility to slow below 200 knots on final, otherwise landing is impossible.
So, wake up ATC folks, and pay attention.
If you find that pilots are not maintaining proper spacing, keep 'em in the hold longer, or provide longer radar vectors, OR, be more precise as to when the flight is expected to slow.
Unfortunately, many in the ATC profession have forgotten that for many, to go down and slow down (both in large quantities) is quite difficult, if not impossible.
Pilots will NOT jeopardise their airplane just for the convenience of the air traffic controller.
The sooner ATC folks learn this very important fact, the better.