I don't know when this happened, but sometime before 1996 the interval tests were removed from the aural tests. I certainly remember doing them when I was a child, as does every other older member of this forum I've talked to.
Having to take interval tests means the teacher is put in the position of having to teach interval recognition to their pupils. Interval recognition is enormously effective at helping to instill aural awareness, aiding with sight-reading and sight-singing. Interval recogniton also helps you to be able to hear music in your head as you read it, a skill that many music educators consider of vital importance in musicianship.
It's true that instrument teachers are at liberty to teach interval awareness whether or not interval tests feature in exams but in reality many teachers will leave it out if they don't actually have to teach it; this is an unfortunate fact of life.
I was taught my intervals at a very young age and had them constantly reinforced for the aural tests I took as a child, and as a consequence have had an automatic interval recognition firmly instilled. This makes it very easy for me to hear written music in my head before I play it or sing it; shouldn't all music pupils be enabled to have this ability?
To sum up, I can see no good reason why they were ever removed in the first place and feel very strongly that they should be reinstated at the earliest opportunity.
Violinia