YABU @Sassetta for all the reasons that people are giving on here. I really do NOT want to be friends with neighbours. I have been in the past, and it didn't end well, and I prefer to keep my distance from people. Just say hello when I see them, say 'nice weather isn't it?' and then move on.
If someone was posting 'new home' cards through my door and then getting pissy because I didn't go around and thank them for it, I would be really pissed off. You don't give something to someone and then complain that they didn't thank you for it. Kind of negates the 'good deed' of giving, because it looks like you are only giving to get some kind of praise for it.
Have you berated said 'new neighbour' to other people? (I bet you have!!!)
I am willing to bet that the new neighbour doesn't want to be friends with you, or even be sociable in any way. And that is fine. Their choice. I know a number of people in my village who were pally/chummy/BFFs, with their neighbours, for several years, and it was all OK, til it went wrong, and they ended up as neighbours at war.
In many cases, one had to move away, as it became untenable for them to stay.
As some posters have said, it is a reasonably nice gesture, (giving a new home card!) but people are entitled to not want it/not like it. Not everyone is the same. Some people might think if they seek you out to thank you, that you will expect them to come into your house for coffee, and then expect them to ask you around, and will want to be all chummy and pally. 😖
Some people just don't always like 'nice gestures'. Like when I am walking towards a doorway (but say, 30 feet away from it,) and someone holds the door open for me, I hate it, because I feel like I have to rush as they're bloody waiting there. I also hate someone saying 'after you' when we are walking fairly close together and the path narrows and it's single file, because I don't need to be told I can go before you, I was going in front anyway. I don't need your permission.
Also, when me and DH were out with some of his colleagues some months back, one woman kept trying to buy us drinks .. She DID buy us drinks actually - 3 each. Even though we turned down 2. But she refused to take a single drink back. I felt offended by it, because I thought 'is our money not good enough for you? and 'do you think we're poor and can't afford to buy you a glass of fucking white wine?! 
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