@Andrewn I'd guess it's not always an active rejection, but sometimes a lack of interest in something that doesn't offer them anything they can't get more easily. If what's on the menu is some kind of generic niceness or generic conservatism...well, you can get that at home.
Fr Robert Taft of the RCC said somewhere (I'm paraphrasing) that people like to go to church do so something: get hit with something, eat something, get rubbed with something, carry something...at so many churches there's very little to do as part of the worship except maybe sing. Obviously you're not going to just walk in somewhere and participate in some kind of involved liturgy, but you might see people doing it. I admit I found that very attractive at the OO parish I visited once (very few attendees, but they were in and out of the altar and doing things the whole time) and also at the first EO parish I attended: clearly people in street clothes singing part of the service, others lighting candles, shuffling around, moving slowly, praying, venerating icons, attending to children, moving something or other...it made a big difference. If we're talking liturgical churches here, I bet the involvement of the laity in the liturgy (or doing something other than sitting during the part the clergy do) has a lot to do with how newcomers perceive it.
Also, people have just as much interesting in healing and transformation as they ever did -- look at the neck-cracking videos on youtube: freedom (from pain), release, relief after 20 years of stiffness...it's the same faith-healer or snake-oil stuff. People always want that. But these days it's hard to encounter that in a church. Very often the central notion is something pleasant, but that doesn't lead anywhere: conservatism, acceptance, presence or absence of a rainbow flag...and there's not a lot to
do in a lot of churches, and not much promise for change.
So I bet part of what's rejected is the perceived invitation "give us your money and your very precious free time and energy, so you can either get what you could get for free anywhere, or get nothing, and do nothing but wish you weren't here."