What's wrong with:
1 "Turn left heading xxx"
2 "Descend to altitude 2500 ft"
3 "Continue the heading, when established on the localiser, descend on the ILS, QNH xxxx"
?
Two things -
1) the aircraft often establish on the localiser whilst level or descending to 4000ft and a) there is often slower lower traffic to be passed before further descent, or b) the aircraft is not permitted to descend further because of minimum radar vectoring levels (ATSMAC refers) - terrain or obstacles in other words.
2) The UK CAA says that you should not use the Glidepath beyond its protected range (which is much less than the Localiser protected range) so the choice is continue vectoring until inside or below protected range/altitude or allow a Localiser lock-on then give descent to allow a glidepath intercept within the protected area:
what is commonly done is:
a) 'xxx turn left heading yyy closing localiser from left/right report established;
followed when possible with
b) 'descend to altitude 3000ft then further with the glidepath'
So we do actually compress the suggested 3 Tx into 2
DD