These novelty sequences have always stood out as tacky. For one thing, of all emojis to include as compose sequences, why these four? "LLAP" is branded, "FU" could be interpreted as offensive, "poo" is repulsive, and "\o/" has no other unique qualities. If people want a more robust selection of emojis to compose, including these four, they could easily use an emoji menu.
Other emojies such as White Smiling Face, White Frowning Face, Black Heart Suit, etc. are left alone because their characters predate unicode, and by extension, emoji as well.