It's how the CBC is structured. They receive funding from taxes and their own revenue streams: merchandizing, advertising, syndication, and so on.
It works. That is, it works until it doesn't.
The CBC is entirely "free" to every Canadian who wants to use it, and it is fantastic. I wish it were expanded in scope.
But there is an opposition that wants it dismantled and moved from government funding at all costs. Usually, the opposition is purely along political lines which is disappointing.
So, I suppose the argument against it being tax-funded is that it become yet another chip in the political game. An argument for tax-funded is that there are no additional fees awaiting those who cannot afford them.
Seems like something of a tossup or...yet to be determined.
The added separation from political influence is big points, but it's rather moot when one group who've already made their mind up will just shout "conspiracy" and then the facts don't matter anyway. That happens here in Canada, to be sure.