Mr. Hat, it'd actually work better based on speed inside say 30 miles than type. A turbo-prop will run an Airbus down any day - not knocking the bus just that they're often slow down final.
We know that giving you speed changes once you've commenced descent is a pain but the sequence is a dynamic beast, particularly when many aircraft are nominally arriving at around the same time - a small change can shuffle the sequence significantly. There are a myriad of things that cause this.
A couple of aircraft who clearly have incorrect estimates (say a turbo-prop is grounding 20kts faster than expected or an International heavy is on an early descent & has already lost three minutes). We try to allow for this but sometimes we guess wrong. Sometimes these things get spotted later than is ideal because we're busy separating.
A heavy has a rethink & decides he needs a longer runway, or the wind picks up a bit & is too much for the guy we were sneaking onto a different runway ahead of everyone. Conditions improve and we can shorten a few up, opening the sequence up ahead of you. Or vice versa & we have to wind the acceptance rate out a bit, as well as allow for the loss of track shortening. Etc.