Many Christians feel that Jesus abolished all other laws except the 10 commandments, when many of them have not yet been fulfilled (Matthew 5:17). In fact, if we study the scriptures carefully, only three of the festivals/feasts were fulfilled.
At Pentecost, the Holy Spirit came. That is another occasion that we have neglected to celebrate according to God's calendar. SDA Pentecost does not fall in God's time line either, as SDA church leaders have chosen a convenient day for "Pentecost and More". Generally, some other churches name themselves after the feast, for example Pentecostals, and totally ignore this celebration of the anniversary of the Holy Spirit entering the church. Instead, the church leaders chose to remember Azusa Street Revival.
The Day of Atonement - which is believed to be of special significance to SDA theology is also not commemorated corporately or even on the correct day. However, Feast of Trumpets is all but ignored in SDA theology, despite the fact that it comes before the Day of Atonement.
It is a pity that some feel that Jesus abolished all other laws except the 10 commandments, when many of them have not yet been fulfilled. While the sacrificial ceremonies have been abolished (or perhaps suspended since G-d promised Phineas the Levite an everlasting priesthood in Numbers 25:13), because of the fulfilment of Jesus as our sacrifice, it was not God's intention that we do not commemorate these special seasons, especially those with future meaning and significance. They are still his Feasts, even the Sabbath (Leviticus 23:2).