Like everyone, I definitely agree that removing votes without reviews is great. Those haven't been allowed now for almost 2 years and they didn't even give any context to developers or users at that time anyways, so loosing them is no loss.
As for the older reviews themselves, I'm more concerned about those for the reasons above and also from a user's standpoint. What happens for the user's who's votes are deleted? Will they even know that their opinion has been removed? Can they leave a new review again? Can a developer, if they know who once left a review was (it's public) contact them (under the guidelines of the JED) to ask them to leave an updated review?
My suggestion would be to have a rolling vote tally system. Basically, the 'vote' score is simply calculated on all votes from today - 2 years. That will make it so we don't need this 'culling' periodically as the system will always be up to date, but will leave old reviews in for context. All reviews that are 2 years+ from 'today' can have a different background color or moniker or something. These 2 things should be easily implementable (a minor tweak to a SQL query and a CSS class for coloring), so not talking anything crazy here. Of course, everything is more difficult to do than said
The reasoning for keeping old reviews is that they still have valuable information as to whether a developer supports their users and extension. While the version reviewed is certainly (hopefully!) out of date, the review still shows a trend over time that shouldn't simply be deleted and may talk about things other than the extension; mainly, support. The end-user reading those reviews can decide their value if they want to page back that far. For commercial extensions, especially, this is important as people don't want to hand out their money without doing their research first.
I'm excited to hear about a possible overhaul, but I think the above is a good transitional measure that, again, shouldn't be too difficult.
Alex Andreae | SourceCoast Web Development
Developers of JFBConnect - The easy Facebook integration suite that's used
on the JED!https://www.sourcecoast.com/