I don't think Apple intends iWork to ever really be an Office replacement in the sense that it will do every single thing you can with Office.
I think their goal for iWork is to just have it do 90% of the things that most people use these types of apps for, even if that means only doing 10% of the things you can do in the Office counterparts.
They have been steadily adding small updates so that it takes advantage of new OS X/iOS features, so it's not like they are just letting them completely stagnate.