Agree, way too much information, however we are required to get all the information from you, so better just to give it all to us, so we don't have to go back and ask you for it over again
As for runway, QNH, type of approach and ATIS information are all mandatory according to ICAO, so no chance of getting rid of that (I know a lot of controllers don't really care about getting those read back at both our and other airports, but that is what is mandatory.)
As for aircraft type, you will be surprised how often it is the 'wrong' aircraft coming, specially on the shorter flights around from around the region. For the time being we are only allowed 5NM spacing in our airspace, so the main reason for checking the type is so the electronic guidance system is correct for when you park at the gate. However, from end of June (or July, don't remember right now) we will get 3NM spacing in the airspace, and then it is quite important to know if you are in an A320 or an A340, so we can put the guy behind you the correct distance behind. But with the high runway occupancy time at OMAA even 5NM in trail is pushing it...
As for RNAV capability it is again an amazing amount of flights that are incorrectly filed, so it is nice to know (however again, on an inbound flight you are already cleared by ACC for a RNP1 or 5 star depending on your flightplan, so if you accepted that clearance I cannot really understand why you have to tell us which STAR you are on (ACC should have told us if you are cleared differently from your filed flightplan)).