I agree with having a balance, and flexibility and graciousness on both sides (host and guest). Think how generic many weddings would be if the HC pitched things solely towards what they supposed the majority of their guests would like. On the other hand, we have many threads here about HCs who went overboard personalizing their wedding to the point of alienating guests--insisting that guests wear specific colors or costumes, for example.
I think the groom's music playing during the early portion of the reception, when people are eating and chatting, would be a great compromise. Then the specifically dance-oriented portion could have more traditionally danceable songs, perhaps interspersed with some of the groom's more danceable favorite songs. A good DJ would presumably familiarize themselves with the requested music (even if they didn't know it before) so they could create a harmonious mix.
As I said before, I don't dance, so I don't see dancing as a requirement for a reception or for having a good time in general. (Unlike, say, having food people can eat or places to sit.) But if the HC really want people to dance, they need to make reasonable compromises to facilitate that--for example, maybe they would have preferred a smaller, cheaper venue, but it didn't have room for a dance floor, so they went with a larger, more expensive venue that did have room. Likewise, they need to make an effort to include songs that people in general will dance to, into which they could incorporate more obscure stuff once people are in the groove.