My name is Petyo Ivanov, and I am the developer responsible for the Kendo UI mobile components design and development. There are few major factors regarding the development (or, more like the lack of one) regarding this issue.
Second, the WP platform so far does not show any signs of market share increase. This, combined with the complex WP8 debugging/inspect/profile support for hybrid apps makes issues like this very hard to address while providing little to no value to most of the users.
Last but not least, I want to mention that we tried to tackle the issue on several occasions, each time resulting in a failure (not to mention many development hours wasted). Given that and the viable alternative present, we will definitely need a major event (for instance, the next IE release, which may improve something), before we look into it again.
Again, I am sorry that things don't perform as expected out of the box in that case.
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