I imagine the long-winded version is used because it contains no ambiguity. This is not so true of the two examples you give, as there is only a difference of one word and I suppose a pilot could assume he/she is able to descend when they haven't been cleared for this.
I found the new phrase a mouthful, especially as the full phrase is:
"turn left heading 110 degrees, report established on the localiser, when established on the localiser, descend on the glidepath."
... so I understand where your concern comes from regarding language. Have pilots actually had to ask you for clarification of what is being asked of them, or just mentioned it as being an unusual phrase?
At most units i've visited, people do not seem to use the standard phrase, favouring "turn left/right, heading XXX, descend ILS", which is a truncation of the old phrase.
P.S. NATS, while probably involved in such matters, do not make these new phraseology rules. They come through MATS1, which is published by the CAA.