People don't have to live similar lives to be in love with each other. Solving cases is his passion. Also note that people don't always realize they're that much in love until they lose the person they love. I'm sure if Shinichi had known what would happen, he would've thought more about chasing down Vodka. It was a split second decision and there wasn't time for him to weigh pros and cons. However, Shinichi also believes in justice. Most people, if you ask them, will say that they'd rather sacrifice the one they love for the "greater good." Does this mean they don't love that person? I'm sure not. They're just acknowledging that if they can save more lives, they would choose to make a huge sacrifice.
Running off in the middle of a date was not Shinichi's fault. In fact, Shinichi even hesitated when he was running off until Ran told him to go. She told him to go because she knew he loved solving cases and because she loved him. The next time he ran off he had no choice -- he was going to turn into Conan.
Again, back to interests. You don't have to share the same interests to love each other. It's often the imperfections and differences that make everything interesting. If you had the exact clone of yourself, one, you'd probably find you don't like yourself all that much , and two, it'd be completely boring. And what does it matter about their parents? People love each other for the person they're in love with, not because of who their parents are. Sure, they may have been raised differently, but when it comes to love, it's feelings.
Anyways, that's my argument that says that Shinichi does not necessarily not love Ran. I can't say I love the pairing anymore, but I personally disagree with your argument that Shinichi doesn't love Ran.