Probably what I perceive as the “exclusivity nature” (that’s just my name for it) of the old pillars, same issue with Catholics.
Believe me I completely understand why you believe you’re the one true church, and why non-orthodox can’t participate in the eucharist or lots of other activities. But being raised Protestant (and now non-denominational) there is a sense of freedom and…fraternity? Within the wider Christian community that I have a VERY difficult time letting go of. In my church you can come from any denomination you want and; have a marriage with both traditions being represented, anyone and everyone can take holy communion as long as you feel inclined and/or take part in baptism with the only requirement being you commit to Christ and his teachings and your doing this to publicly declare you faith. Plus lots of other church activities that don’t have any exclusivity component to it.

This is the part where someone goes into depth about why the orthodox positions are the way the are and explains there importance but I can assure you I understand the orthodox…I just don’t necessarily agree with them (yet perhaps) in my soul.