Okay, that sounds reassuring. Though I would dig a little, frankly - if I had a tenner for every woman claiming the ex "took the piss" when in fact a court had ordered an equitable settlement or the guy was lying about payments I could have a nice holiday. But on the face of it, he sounds like he is being great, and it also sounds like you are both financially secure, without needing a claim on the other.
I'd talk to him. Sit down and talk about why he has gone cold on the wedding. Talk through why it matters so much to you, and why he feels the way he does. Leave the name to one side - it's not fair on the baby to use that as a chip, anyway; I think the name should be chosen on what suits the child's best interests, and a link with siblings may, IMO (though if he has an ex he is generous too, then presumably it will have siblings on that side, too? So maybe his name as a middle name, no hyphen, that is included on official forms might work?).
Do think you should consider whether the big froufrou day is what matters, here, though. Wouldn't a beach wedding somewhere with all the kids and close family be lovely? Or even just the two of you? Still special, still luxurious, but maybe your DP just hates being the centre of attention - which I sympathise with.
I think I lack the bridal gene though, so maybe I just don't get it.