How is that really different though. It's still two different groups invited to different bits? I understand some people may prefer it that way round if they prefer the ceremony to the dancing and socialising (and other may feel the opposite) but it's still 'two tier guests' as people on here call it. I have also been to ceremony and tea / cake after bit not reception for a couple of religious people and was very happy to be there, but in my head it was their version of someone else I inviting to evening only.
I'm happy with an evening only invitation, although how much I enjoy them usually depends on who else is going and how up for a dance etc they are (but then my enjoyment of the whole day would probably also depend on who else was there). I do think the examples here where people were just left outside waiting are examples of bad hosting and rude though.
We had a very small ceremony/ reception (20 people) then around 70 in evening. I'm sure everyone on Mumsnet thinks we are terrible, but it suited us - we didn't want to have to do vows, walking down the aisle etc in front of loads of people, or to spend the money for a sit down meal for 70 people. However we did want a party with people we cared and about and didn't want to leave them out all together. We did consider being brave and having everyone at a late ceremony and then going straight into an evening party with substantial buffet, but we had DHs grandparents to consider and thought they'd want a sit down meal etc and actually we wanted to make more of the day for us too. Our evening do had disco, decent buffet, arrival drinks and cake cutting. I'd happily go to a birthday party that had less, so I don't see why suddenly when it's a wedding that's a terrible event / imposition. Most of our evening guests were local but a few travelled. I wouldn't have been offended if they hadn't though. I have also travelled back for their evening dos in some cases.
I know a lot of people are saying book the wedding / venue where you can afford all those people, but realistically there is no cheap way of doing a sit down meal for 100+ that I know, and you can bet if you only have a buffet in a hall for a full day event there would people on Mumsnet complaining about that too... People on here love to complain about how they don't think they've been treated well enough at weddings!
I'm going to an ex colleagues evening do next month and very glad I am. If it came to a choice of not being invited at all or just going to evening, I'd much rather have the option of evening.
If course don't go if it doesn't sound like something you'd enjoy it travel too much etc, but bring offended by the invitation and having blanket rules about all or nothing is cutting off your nose to spite your face I think.