Bollywood movies produce fine and realistic movies compared to over the top action movies by S India. Only reason Bahubali or Robot is getting any importance in north is because of their Graphics and VFX, no one cares about rest of the unrealistic action movies with crappy looking actors that South produces. Don't get carried away here.
This couldn't be farther from reality.
90% Bollywood movies are either unrealistic crap that tries to imitate Western culture partially or completely and FAILS MISERABLY, or unrealistic crap handpicked from the South and remade.
If you take Southern movies altogether, the four languages, you'll get a 50-50 realism-unrealism, with particularly Malayalam leading in realism. (Other languages tend to go more unrealistic, but they more than compensate with proper cinema.)
Why the South Unrealism image you ask?
See:
I've the greatest respect for some directors from the southern movie industries, whose movies northerners will have no clue about, since northies want only masala movies from the south on their t.v., or remade in Bollywood.
(Creating the misinfo that southern movies are non-sense. Reality is that northern market wants only the non-sense.)
Check out National Awards list for more.
Another important thing to note is that the technicians in Bollywood tend to be from the South, which explains the technical brilliance of SOME Bollywood movies. (Not Ra One tier crap. The realistic movies of Bollywood.)
More Money + Talent = Technical Greatness.
Overall, sorry, but Southerners are better filmmakers. Bollywood wouldn't be where it is today technically and artfully (whatever there is) without the Southern artists.
Meaning, this is not North vs South.
Merely industry vs industry.
Just because Bollywood uses Hindi doesn't mean anything.