John_1851,
From the way that you're speaking, it seems to me that you're not a software designer or programmer, and that you therefore don't quite understand the limitations and difficulties associated with using development tools. As a programmer myself, I understand what Bob is saying and do sympathize with the position the TurboTax team is put into by Apple's continuous "move forward" policy regarding their OS releases.
If there is anything to be blamed here, it is not the TurboTax team; it is Apple, for continuing to advance their operating system's features and capabilities while choosing not to support their old hardware for nearly as long as Microsoft does. If Apple had continued to support technologies like Rosetta, or made it mandatory for developers to continue supporting 32-bit apps, perhaps the situation would be different. However, the new version of the development tools that TurboTax's developers use clearly does not support 32-bit apps.
When you choose to use a set of development tools, you're essentially "locked in" to that set of tools. Upgrading to a new version of development tools usually requires quite a bit of work, even if no functionality is added to your program, but to completely switch to different development tools is such a massive undertaking that it is usually not at all cost-effective.
That said, TurboTax's developers clearly had to choose this year between upgrading to the new version of the tools they were using, or to stay behind. It was clearly not an easy decision, but their bean-counters (who, mind you, have access to full statistics that we don't have) obviously decided that the benefits of upgrading to the new tools--which included the added exposure and accessibility provided by the Mac App Store--clearly outweighed the drawbacks. Do other sets of Mac OS X development tools allow for both 32-bit support AND Mac App Store support? Perhaps they do, but since TurboTax's tools do not, it's out of their control. Development tools are, like other software, sold as a set package. One customer can't just ask for a new feature to be added that would benefit only them, regardless of what software product we're talking about, because it's just not cost-effective...therefore, TurboTax cannot ask their tools provider to add 32-bit support.
I'm sure the fact that old customers would be left behind was considered, but please realize that the company IS providing alternative methods to obtain their services, in the Online and iPad versions. Apple, on the other hand, does not provide a way to install newer OSes on their older hardware, including your Mac. TurboTax should be praised for supporting your Mac, even after Apple themselves abandoned it. However, because of Apple's "move forward" philosophy, this will be one of many new products you'll find yourself unable to run because you are using an older Mac. I will be shocked if any new software products support OS 10.6 two years from now, and I say this as an OS 10.6 user.
~Aaron