Jeff: They might be
effectively leavened, but that's the whole point of a legal system, and of scholars to interpret it. What looks to you (or me) as a layperson like the same thing might not be the same at all. In this case, the technical definition trumps what might seem like leavening to you, because of debates and decisions that rabbis had about 2,000 years ago.
Of course, you can decide not to eat such kosher-for-Passover products. I do know some people who refuse to eat things that look like the year-round versions, because they feel like it's too close to the "real" thing."
As for sparks and electricity, the legal reasoning has nothing to do with "work." It has to do with "melacha," which is often poorly translated as "work," but has absolutely nothing to do with physical exertion. Rather, it has to do with creation, destruction, or just changing the nature of the world.
For 2,000 years, Jews have avoided anything having to do with light or fire on Shabbat. Electricity posed a bit of a problem -- here was a way of lighting and heating that was previously unknown, and which didn't fit previous legal categories. Should it be allowed or not? There were debates over this, and many Conservative rabbis argue that it's totally OK to use electricity on Shabbat.
I grew up in a home that used electricity on Shabbat, and I slowly came to the conclusion that even if it's permitted to use electricity, my Shabbat is radically enhanced by not doing so. Not using the computer, not using the phone, not watching TV -- these make my experience better and special, rather than worse.
Is that sometimes a pain? Yes, it is. But I have found that the trade-off is more than worthwhile.
Moreover, as I wrote in a previous comment, much of Jewish law is a forcing function toward community involvement. By forbidding people to drive on Shabbat, you increase the chances of having a culture of home hospitality and spending time with friends -- something is nearly universal among people who don't drive on Shabbat, and something which is almost completely non-existent among those who do.
Even if you could argue that driving a car is OK on Shabbat (and there are very few ways to justify that; remember that it's also forbidden to drive a horse or ride a bicycle), the social ramifications that I've seen are almost entirely detrimental to the community. Non-driving communities tend to be much closer knit than those in which people do drive.
So, why not do these things? Because it changes the way in which the day operates -- for you, for your family, and for your community. This doesn't mean that it's meaningful or appropriate for everyone, I'll admit.