In 2G 1GB is enough but in 3G or LTE 1GB isn't enough for a month so Look at ₹300 for 6 GB for 28 days. That is Rs 50 per GB without WiFi data. That is a big point as not even 1% people will use Jio WiFi data though everyone will get it bundled with Jio basepack.
Just look at Jio ₹499 Plan which comes with 8GB WiFi data but only 4GB LTE data.
Now people can take Jio ₹149 base pack +301 addon =₹450 and get 6.3 GB lte data.
So this combination is more beneficial for people as they get 2.3 GB more LTE data by paying ₹50 less.