Because Starcraft is dead.
LoL is the biggest Dota-like, and they have intense policing and professionalism. It exists for people who want that. Dota's esport was built on the back of a grassroots community, and you can't exploit the same community and then throw it by the wayside because you wake up one day and want to be ESPN.
It is just a shame that it is very off-puting for new players.
Regardless of "Esports", recently I tried to introduce a friend to dota. Imagine if I showed her this particular cast, it would have turned her away from the game as a whole immediately. I understand there is an audience for this type of casting but it shouldn't be the primary stream cast in my opinion. Professional casting shouldn't be dull. It should make the exciting parts more exciting and the lulls in the game feel less so.
As a casual dota player I don't know who is friends with who or what the history is. Should that bar me from watching? Or should I first invest in knowing the entire history? I can watch a football match without knowing where Messi played before or if he ever had lunch with the caster.
You have three sides now; the tightknit community that plays since the dota1 era, the esports, and the new (casual) players. To me it seems that these sides are in conflict at the moment. There is fear that making the game into an esport will make it boring and stiff. While the esports side wants to make this bigger but needs the core community for it. Meanwhile, the casuals get reported for not picking Kardel "but I can't find him!".
I hope these sides can exist next to each other. For example TI4 had a noob friendly stream, why not have a 'core' stream? If Valve does not want to invest in the casters, opening up the stream (for a cost if they must) could be an option.
Note that I left out the general treatment of James and Valve's handling of events which seem terrible all around. Just wanted to include my view point from neither the core community nor the exports side.
