I don't see why it would have to be paid for. I already pay nearly double what the US pay for the same software. And I'm being asked do I want to pay more? Should I pay for any feature that is requested? Like the improvement of footnotes? Should I have to pay for better paragraph numbering? Or any feature that is new or any of the updates that come out?
Saving back more than one version is certainly an issue. It's a hot topic for sure, but getting it back more than one version has to become a reality soon. What they do to get it back and how they go about it is up to them. This is asked on Adobe forums and in the adobe help file comments on a regular basis. So if there's a demand for a feature why not give the people what they want?
Look at it this way – sooner or later CS6 will be here. And you will have people, new to InDesign buying this latest software. Now they have to go and do business with other companies. Some on Cs3 some on CS4 and some on CS5, is it fair that they will only be able to only save back one version? Or that there isn't an update for CS3 and Cs4 to open IDML files created in CS6? Where is the option to even buy CS3 CS4 and CS5 for the upgrade price if you purchase CS6? Will there be one? You can't do that now. You can't even get a demo of CS4 so you can save CS5 to Cs4 to CS3.
All it has to say is “Warning: Layout may be altered as some features are not supported in this version of InDesign”.
We can argue things about features and what do with them until we're blue in the face. Frankly, I just want to be able to save back more than one version. It's not really my concern how it is accomplished. It's just something that needs to be addressed.