I've wondered about that too, but I think what I've seen in Orthodoxy is not so much that it represents a static fixed precise copy that hasn't changed since Pentacost; but more that the Church established by Christ has grown where it needed to grow- not because of definciency. When a farmer plants his field with seed, the seed is what it is- and yet looks different in some ways at its harvest. Still that seed, while growing, is still what it is, having grown up within the confines of that which the farmer marked out. I think that while Apostalic Tradition and the Scriptures marked out the boundaries of the Church, that wasn't to say that she needed to remain in static form, so long as she stayed within those perameters- interestingly enough, seed that lands oustide of those areas doesn't seem to tend as well, could that also apply here?
In any case, I submit the changes are both growth and weeding, in a sense. These things you bring up don't put the Church outside of Apostolic Tradition, but allow for the growth that I think Christ, and the Apostles wanted to allow for. Why do protestant/other traditions get pegged as outside? Well, in a highly generalized view, many don't seem to agree with that Tradition. Celebrating or not celebrating a holiday, changing clothes, adding songs- none of these things seems to contradict and Apostalic Tradition and may be viewed as a logical conclusion; but what of the Zwingli tradition of the Eucharist being merely symbolic? What of the Sacrament of Baptism being viewed as merely symbolic and almost trivial obedience? They seem starkly opposed to Holy Tradition. These are just examples, and it may not always be so cut and dry, but just my thoughts on the matter.