And you say the countries want to join and that's enough? Huh, maybe we can evaluate their motivation for wanting to do so? To use a different example, if a partner wants to break up with you, would you ask "But why?" or do you just say "OK, you want it, so that's enough of a reason."...
Joining NATO is not like taking a membership card at one's local gym when one feels like it. If, say, Sierra Leone "wanted to join" it's unlikely it would happen.
NATO is a military alliance. It has a purpose, it has a governance and it doesn't just randomly expand to whichever country feels like joining. It's understandable that analysts analyze the expansion of NATO in a broader context. It would be naive not to.
Kind of like it’s your neighbor’s business if he runs his leaf blower 4 hours a day. His lawn. His choice. If you get angry about this, you’re just being irrational. Probably isn’t even about the leaf blower at all. You’re just using that as an excuse. In truth, you just want to extend your influence and throw your own weight around.