Apple's behaviour has often irritated me as well, but that's hardly fair. We've all known since it was first introduced that Rosetta was a bridging measure, just as was Classic, and that, like Classic, it was going to disappear at some point. Nobody has pulled any rug from anyone: you're not forced to upgrade to Lion. It's for you to balance any potential benefits (of which those of us who don't have privileged access are, as yet, largely ignorant) with any disadvantages, such as being unable to run PPC software.
If previous experience is any guide, essential software for which Lion is a requirement will take a while to arrive and in the meantime there will be little downside to continuing to run Snow Leopard or even, as I still use on an old PPC-based tower, Leopard.
Computers are not bought in isolation. Like cameras, they are part of a system that is intended to last a long time.
We all knew that film SLRs were on their way out when Digital SLRs came along. Yet, the Canon 7D I just bought is 100% compatible with lenses that were purchased in the 1980's. Lens that I buy today have features that were not envisioned in 1980 (such as Image Stabilization), yet these lenses work with full functionality on a film SLR from the 1980's.
Imagine if one of the major camera manufacturers announced that new DSLRs would only work with lenses made in the last three years, and that new lenses would not work on old bodies. I suspect such an announcement would promote a switch to another brand.
As to being not forced to upgrade, that's not quite true. Apple doesn't support hardware more than a few years old. When the hardware dies you have to buy a newer model. Those newer models won't run Snow Leopard (even though they have the horsepower to do so).
Compare this to the Windows world. I can buy a computer today and install XP on it. Microsoft is still providing security patches for XP. In one of my jobs we have a dedicated hardware system that is run by a 20 year old DOS program. We recently bought new computers and they run DOS just fine (the BIOS even includes the code necessary to make the SATA drives look like ATA drives to DOS). Sure, we could spend tens of thousands of dollars re-writing the system to be more modern, but it's much more economical to just buy a new PC and install DOS.
The downside to continuing to use Leopard is that it prevents you from upgrading other parts of your system. Want a new iPhone or iPad? By December you will need Lion.
But the real issue is that Apple is phasing out the Mac. Lion is likely the last version of the Mac OS. Apple is moving towards the computer as an appliance. After Lion, the Mac will run iOS 6. Gone will be the days of a configurable computer. Most people don't need a color managed workflow, so Apple will drop that. Most people don't need to be able to work with RAW files, so that will be gone too.
If there is one thing that Apple has clearly demonstrated, they don't feel any need to support their high end customers. Their ultimate goal is an integrated system based on their
cloud. The mass of non-techies is their audience. Apple will provide the solution that they think is best, and if it's not the solution that's right for you, then it is your tough luck.
To be fair, most people don't need these features and most will be happy with Apple's decisions. I just think it's a mistake for a high end user to plan a future based on Apple.
Take a look at what's been happening with Final Cut for a good example. Have a library of Final Cut projects? Sorry, you will no longer be able to edit or update them on any new computer. The old version of Final Cut has been discontinued and the new version cannot (and will not) open projects from the old version.