In my view there are really 3 basic options here for Adobe to offer users:
1. Users must pay money to upgrade to the latest CR to get the latest camera support. No options available for older versions of CR to process raw files from new cameras (except for those models that shoot DNG, like the recent Pentax models, the Leica cameras, or the Casio EX-FH20).
2. Users can either (a) pay money to upgrade to the latest CR to get the latest CR features (e.g., adjustment brush) and non-DNG raw file support for latest cameras, or ( keep their existing version of CR and get DNG raw file support for the latest cameras, at no extra cost.
3. Adobe provides non-DNG raw file support for the latest cameras to all previous versions of CR (or at least some # of versions back).
There are tradeoffs with all 3 of these. (No, it's not a perfect world.)
The obvious problem with #1 is that photographers with older versions of CR really have no options (and I literally mean ZERO options) other than to upgrade if they get a new camera which has a new non-DNG raw file format. Adobe could very well have taken this approach but chose not to. It's good for Adobe's dev team but uncool for photographers.
Approach #2 -- the approach Adobe has taken -- makes sense in that you only have to pay money if you want new features: specifically, things that actually improve image quality, workflow, or both (e.g., new tools, like the Adjustment Brush or Gradient Tool, or the new ____ and ____ tools in the next dot update of Camera Raw). If you have no need for these new features, then keep your money. You can still process raw files from the latest cameras by using the DNG route. The downside is the extra step in the workflow of creating these DNG files first. But it's free. This is a reasonable tradeoff IMHO.
Approach #3 sounds nice to users but has several problems. First, it's not technically possible to retrofit latest camera support into Camera Raw 1.0. So even if we added non-DNG raw file support to some earlier version of CR, where does one draw the line? 3.x? 4.x? Wherever you place a cutoff, folks who just missed the cutoff get upset. Second, the (very small) CR core engineering and quality engineering (QE) teams would be spending the majority of time retrofitting new camera support into older versions of CR, instead of pushing the product forward. Remember, adding camera support isn't just a matter of copying profiles or merging code. It also requires a lot of time to test to make sure everything is solid (i.e., all the interactions work out).
But for the sake of argument, let's say we (at Adobe) just put our heads down and did the work anyways. The real problem with going through the effort of putting support into older versions is that it produces zero improvement in image quality and zero improvement to workflow. Let's be very clear on this, with an example: if we added Canon PowerShot G10 CR2 support in CR 4.x, there would be no difference in quality compared to using CR 4.x to process a DNG created from that CR2. So, #3 really amounts to Adobe spending a lot of time doing work that provides no improvement to quality or workflow. Consequently, users would then have to wait longer and/or pay more to actually get those features that folks have been asking us for (Barry F. started a recent thread on this). Ultimately not a good position for either Adobe or photographers IMHO.