Yes, that is true, but the reason the fleet is so senior is because it has a large amount of very nice destinations and a lifestyle to suit. Senior pilots wish to share in it and have the seniority to do so. A mix of short and "medium" haul is seen by lots of people as being ideal.
Destinations such as Madrid, Rome, Stockholm, Edinburgh, coupled with Chicago, JFK, Nassau, Dar es Salaam, Tel Aviv, Moscow..the list goes on.
I know this doesn't really address the issue that one does not have much control over one's roster, but at least you are pretty certain of going to nice places...