And here's why:

1) it taught me that it's possible to really, really not like someone but still treat them with respect. It taught me to how to forgive but not forget.
2) it taught me to take down walls I had put up and come to see my stepdad as someone who really, really loves me.
3) it taught me how to share, because I got stepsiblings.
4) it has made me a more patient person.
5) it showed me exactly what not to be as a SM.
6) I had a few really bad bosses whom I did not like. Having learned to treat my stepmother, a woman I've never been close to, with respect as an adult authority figure helped me have more patience in dealing with these bosses than a lot of my colleagues had.
7) it taught me that sometimes you have to make the best of choices that others made that you don't like, and
that you can't control others, and you can't control all situaitons, but you can control how you behave. If you choose to behave and be civil to a stepparent (even if you don't like them), you are making yourself a better person. If you choose to be rude to that stepparent, life will be much less pleasant for everyone in the long run. If you choose to get to know your stepparent, you could become really close with them and you'll show them why mom/dad loves you so much. If you choose to not get to know your stepparent, you could be losing out on someone who could really come to care about you.
9) Sometimes you have to make compromises in situations you didn't make (your parents divorce and remarry other people). This has also served me well in the real world. Some difficult situations at work arose due to the choices others had made in the past. I made compromises with others. Again, I feel that I had more of an ability to do this than some of my other coworkers because of my stepfamily experience.

Don't get me wrong, things aren't, and will never, be perfect. There are still a lot of times where I get frustrated about my stepmother and how she treats people. I've just developed a lot more patience regarding how I deal with it.

Please show this to your partners. They can use these situations as teaching tools for their kids. Their kids will have bosses and teachers they don't like but they'll still have to treat them with respect. The same should go for stepparents (unless they really jerks). Yes, we as stepparents will have to make some compromises for them, but good, truly loving parents do not thrust their kids out into the real world with no training/preparation/experience. There are ways to be a loving, affectionate parent who has a great relationship with your kids while also teaching them healthy boundaries and giving them discipline when they act up. No, the kids will not adjust to this stepfamily overnight. It took me years. But doing these things can help them come to accept it.