It doesn't bother me either way - whether I'm solo or with one or more people in my party, if we're sat with other parties, I play off them. I'll say hello and laugh and be friendly when they sit - if they respond in kind, then we'll chat and laugh and interact the whole way through. If they don't, then I mind my own business and stick to myself or my party. Even when it's at a table, it's still like any other social environment with people thrown together - some like to interact, some don't. I'm not offended either way.
I've done 30+ cruises in my life with shared tables at dinner, done shared tables at bars and restaurants, sat next to hundreds of people at bars. A vast majority of the time, the others have been friendly and will chat at least a little, and then we go our own ways after. A few times at Disney I've even bumped into people I shared a table with somewhere else in the parks, and just give a friendly smile and little wave just to acknowledge. A few times, I've gotten very unsocial folks who just didn't want to interact with anyone else, so we just shared the table and stuck to our own groups, with no offense taken, and parted ways when done.
And a few times, I've shared tables with people and gotten along so well that we had a great time, even planned to meet up again, sometimes exchanged numbers, sometimes stayed in touch, visited each others' houses, and went on other trips together. A very good friend I met on a cruise 24 years ago lives near London, and we've stayed at each other's houses, done two Disney trips together, and gone on 6 other cruises together. I've had cruise mates from Philadelphia, Los Angeles, Germany, Australia, and Ireland stay at my house, planned Disney trips with, and stayed at their houses when traveling to those countries or places and still keep in touch 10-20 years later. A few folks I met at Disney I've made plans to meet up during subsequent trips and have become e-mail friends. Sure - probably 1% of all the people I've shared tables with have actually become friends, but probably 80% have been cordial and friendly and interacted well and 19% just didn't want to socialize and did their own thing. If I'm on a cruise, or at Disney, it doesn't bother me a bit either way - I'm going to enjoy my trip with my party or by myself!