Evidently the WTS has had enough complaints to address the problem of people attending receptions without an invitation. It is totally selfishness on their part which seems to be a trait among many jws.
*** w00 5/1 p. 20 Joyful Weddings That Honor Jehovah ***Unless it has been stated that a reception is open to all, a true follower of Jesus would avoid attending a wedding reception uninvited and partaking of food and drink provided for the invited guests. Those tempted to go uninvited should ask themselves, ‘Would my attending this wedding feast not show a lack of love for the newlyweds? Would I not cause inconvenience and detract from the joy of the occasion?’ Rather than take offense at not being invited, an understanding Christian may lovingly send a message to congratulate the couple and wish them Jehovah’s blessing. He may even consider helping the couple by sending a gift to add to the happiness of their wedding day.—Ecclesiastes 7:9; Ephesians 4:28.
*** w69 5/1 p. 284 Social Events Need Christian Moderation ***After a wedding in Toronto, Canada, the couple shared a "sit-down" meal with only a few very close friends and relatives, and they later had "open house" with light snacks for the congregation in general. Following a wedding in Düsseldorf, Germany, just sixteen were at the feast in a restaurant. This allowed for relaxed conversation. The money saved by having a small gathering was wisely put to use by the couple in their new assignment as special pioneer ministers. True, others might have liked to be at the celebration, but they understood that the couple could not, as the groom put it, "invite all." However, they were pleased to share in the couple’s happiness by being at the Kingdom Hall for the marriage talk.
So whether a wedding feast will include many people, or just a few, whether it will be by invitation only, or "open house," or whether a reception will be held at all, can be decided by the couple getting married. Those who have cultivated Christian moderation will "live with soundness of mind and righteousness and godly devotion amid this present system of things."—Titus 2:12.