I think Bundesliga has benefited much more from Bayern going massive than it did when Bayern was average a few years ago.
The problem of Bundesliga is how poor it was marketed (is that even a word?) outside of Germany. They finally managed to get a global TV deal last season, and obviously for peanuts compared to EPL or La Liga. The league being in german language also is a huge barrier, not to mention he huge and progressive lack of foreign players because Germany actually produces their own talent.
Thanks to the UCL and Guardiola, the league has gone much more global. Now pretty much everyone knows Bayern and Dortmund everywhere. That's huge for the league, having an average Bayern would only make the Bundesliga weaker worldwide.
Bayern gets less TV money than Cardiff City did for last season
You're right.
Nobody cared about the Bundesliga in the 00s. But then the rise of Bayern happened <3