Middlings "What I find weird is, why would they want to come?! I can't imagine wanting to go to a wedding where I didn't know at least one of the bride or groom really well."
OP, are these friends old family friends or new ones? If they are old family friends then you, as the bride-to-be, may not know them but they may know the groom-to-be's mum very well, and may have known the groom-to-be since he was a baby. they may not see him often but may hear stories of him and his exploits all the time from their friend, his mum. They may have attended his Christening, if he had one, brought him gifts as a child and looked at 100s photos of him over the years!
Why would they not want to be there to see him on his big day?
In many cultures a wedding is not just about two people marrying it is about two families, even two communities, coming together.
I still thin the happy couple can veto things but should only produce the 'not at my wedding' card when it is necessary.
The Op may not like it but her dh may have a big fan club of older people who have seen him grow and it seems a bit unreasonable to say no unless her dh to be is also adamant he does not want them there (or these people are actually new friends and unconnected to her dh to be!)
OP do you have kids yet? If no, one day, when you have kids, if you have kids, they may see how much family life is not just about the individuals, wider networks form of people who share common bonds, they may not be bonds of blood but of time spent and dreams shared. My friend kids are very important to me and if/when they marry I would be honoured to attend their weddings.
I mean that in the nicest possible way 