Not if I keep skipping app updates!
I really wish they'd treat mobile device OS like PC OS: something you choose to upgrade, or not, at cost. Yeah, it would play hell with the "walled garden" but as a consumer I don't like being forced into a product change that I didn't ask for.
Ignoring the part where Apple's way is good for Apple's bank account, there are some pros to the current way.
iOS has the highest rate of current OS version adoption. This reduces the testing required to verify compatibility (once upon a time, I worked in QA, I know how to consider all the combinations/permutations that COULD be tested and probably SHOULD).
As a result, a software developer only needs to consider 3 models of iPhone, 3 models of iPad, 3 models of iPod Touch all running the new OS. They might do testing under the previous OS version, but there's little statistical need and they can force you to be current if you want to run the app.
that really reduces the test matrix down by cutting out the OS as a variable. In server software QA, you'd have to test multiple versions of the OS (at least current and one back, if not two) plus with or without service packs.
the less combination testing going on means more focus on functionality testing. Otherwise, to reduce time, the functionality tests are often spread across the combinations (meaning Function 12 was tested on Combination 50, but nowhere else). this gives reasonable spread of testing, but risks a compatibility issue sneaking through, because they can't run every test on every combination.
So the benefit being that assuming the app has a QA budget, the QA staff is more likely to do a better job, resulting in a better App. Which iOS apps do tend to be known for.