I have a landline because I prefer to have my phone tethered to my house. When I'm out, I want to be out. But even when I relied heavily on a cell phone in college I experienced the anger problem, because it was assumed that I always had my phone on my person and was aware of incoming calls. I wasn't. Other times I was out doing stuff and/or just didn't feel like talking right then. For certain friends and family members this wasn't acceptable. They felt rebuffed when I didn't pick up or return their messages right away. "You must have known I was calling you," they'd say. "Why didn't you answer? Why didn't you call me back?" "Are you upset with me?" "Don't you care?"
I experienced the same thing when I dropped off Facebook. Some friends were legitimately sad that they wouldn't be getting goofy pictures of me every few days, and that was one thing. But others felt I was deliberately removing them from my life (the ultimate unfriending?) or was making myself deliberately, aggravatingly unreachable. Note that this was when I was in college, and my dorm room and phone number were publicly listed in our student directory. And I also provided everyone with my personal e-mail address.
Nowadays it's the same story, but the focus has shifted entirely to e-mail. I will ask a co-worker, "Do we know where the office party is going to be?" and their immediate response will almost always be, "Didn't you get the e-mail?!" No, I didn't. I was commuting. And it was only sent eight minutes ago.
Even if I had a smartphone, I doubt I'd check it enough to live up to the basic standards of owning one.
/ramble
TL;DR: No, I would not buy a Nintendphone, even though I think the idea has marketing merit.

