Pilgrim festivals are festivals that Jews would have gone to the temple to observe before it was destroyed to fulfil mitzvot.
Why are festivals important?
Unify the community
Fulfil mitzvot
Teaches Jews about the nature of God
Links to ancestors (secular)
Some Jews may feel that they cannot fully observe pilgrim festivals because of the lack of temple. Due to this they may support the formation of the State of Israel and the possible rebuilding of the temple.
Some Jews believe that having a temple is not necessary to fully observe pilgrim festivals and that God will understand that they cannot celebrate in the temple.