Damn, the end of your post would absolutely rile me up and I wouldn’t be silent. It makes me feel better than my parents are involved. They might even call my boys too much since they live a long way away! My wife’s parents were the same before they passed. Heck, my oldest son would help dress my FIL when he lived with us before he wanted to go back home and passed of cancer. It would suck to know any of the four grandparents wouldn’t do anything for my boys. Definitely blessed.Reading this thread though, there's a lot of us in the exact same situation. Having this conversation is tough, because we don't want to lose the relationship that exists pushing for more. By having this conversation, you're drawing a line in the sand that the relationship as it exists cannot continue. As several people have stated, the conversation can lead to even less interaction and fulfillment.
My wife and I have had the same conversation regarding my father. He and my mom split up when I was two, he remarried a woman that he was counseling and had two more kids with her. I saw him every other weekend. New woman left him after 20 years and he remarried in 2012 to his third wife who had three daughters. I was living six hours away at the time and he got wrapped up in her kids and their life. My wife and I (and our three kids) moved back at the end of 2019, currently about 40 minutes away. There will be birthday parties at his house, they will take her grandkids to do activities and will watch her grandkids when the parents go away. They have never offered to watch mine. We're flying my mother-in-law up to give my wife a hand while I am out of town over Labor Day weekend.
While it does get under my skin, I'm really trying to just accept the relationship for what it is. If I invite them over, they'll generally come. If we invite ourselves over to their house, they're generally OK with us coming by. At the same time, when we get together and the first thing my dad does is tell stories of the outings they had with her grandkids...man I get heated.