'Offended' is too strong a word here. My point is merely that not everyone is living in a cosy family unit. If the card is meant for the general public, it could feel to some isolated people as if they are not included in the message.
The pandemic has really exacerbated feelings of loneliness and disconnection, particularly amongst older people, and particularly at this time of year. Twice as many older people are spending Christmas alone as would be the case in a normal year.
That's the reason I think it would be nice to use more inclusive language.
Of course, if a card is being sent specifically to a family, the members of which are in a caring, close relationship with each other, then such sentiments would be fine.