There is no wisdom in comparing WebM to flash. They couldn't be further appart in various aspects. For one, WebM is hardware accelerated whilst flash wasn't.
There's also no wisdom in Safari preventing users from viewing a widespread royalty free media format. It simply causes frustration which is evidenced by the many frustrated customers in results for "safari stream not working "webm"" search.
How do you know that the iPhone and iPad hardware have the IP core for performing hardware decoding of WebM formats? And how many such searches are actually taking place relative to the number of successful video views?
There's also no wisdom in Safari preventing users from viewing a widespread royalty free media format. It simply causes frustration which is evidenced by the many frustrated customers in results for "safari stream not working "webm"" search.