I'd take it even a step farther, and say they want a 'predictable level of unpredicability' and a 'predicatable type of unpredictability'. I guess that makes it easier to market the product to the more casual fan or something.
The technological innovation and cleverness in strategy were two of the things that hooked me on F1 to begin with, and they're taking that away, bit by bit.
I think if you have "unpredictable types of unpredictability", there are a lot of weird things that can happen. The races can be unpredictably boring, or unpredictably unsafe. Or a team unpredictably (in advance) dominates. Or an unpredictable loophole is found, ruining racing. Et cetera, you get the gist.
I think from an "showbiz" viewpoint, these are kind of scary, so a lot of decision-makers in F1 are, as you rightly say, trying to control and tame this "true" unpredictability, taking away some of the exciting bits as well.
As to the original topic, I think a smaller rulebook is better, and intricate rules governing how you can and can't use tires that are already allocated to you and will likely be discarded afterwards... is a bit unnecessary. I wish the rules were simpler: you have your allocation, so just use the tyres however you want, including mixing the compounds if necessary.