Having a data plan is one of those things you think you don't need, right up until you get one. It's just too useful to give up easily.
That said, I think it's a shame the telecoms have found a way to charge per megabyte (effectively). They missed that boat the first time around, but with cellular data they have consumers pretty well cornered on that one.
It'll be interesting to see if projects like Google Fiber can break that paradigm.
If there was one thing I didn't like it was when I bought I new phone, I wasn't grandfathered into an unlimited or a nice data plan. I'm on a 2 gig plan, and I think that psycologically has forced me to not use the phone as much as I did last year. Even if I'm no where near 2 gigs, I don't even get over 1 gig because I'm afraid I will overuse it.
As for the whole ethical thing, I admit I do use my phone when I'm with a friend, but he does as well. When I'm with other groups of people I don't but I do know that they might. It's a shame that the whole "social" interaction thing seems to be a dying breed. People would rather be on their phones or text than actually talk to a person.
If there is one pet peeve I have (And my friend does this all the time and I hate it), it's when I leave a message for someone and they write back to me on Facebook. It just sucks that I took the time to leave a message and they just wrote back on facebook and didn't even call. That just seems a little rude to me.