Went to a shiur on this.
Meat for Simcha is Shlamim (Korban) specific. If it is not a Korban, then there is no mitzva of eating meat.
Simcha these days is:
Men: Wine
Women: Clothes (Husband MUST provide)
Kids: Candy
There may be minor reasons to eat meat on Yom Tov, but none of them REQUIRE meat-eating.
If one doesn’t want to eat meat in this day and age, it is logical for a number of reasons:
1: Meat is expensive 🙂 Tuition is more important.
2: Easy to get fat on meat 🙁
3: Don’t trust Agri/Alle/other butchers
4: Wastes energy, and causes more fossil fuel to be bought, enriching Iran.
There are many others.
I have nothing good to say about PETA, so I will remain silent. 😐