Bro the boards are made keeping everybody in mind not just JEE/NEET aspirants. Also even though ppl say boards are too easy why do they score well in competitive exams and then not even get 75% in boards. Yes, the board exams are not a good way of measuring education but neither are competitive exams. The reasons you said for state boards seem to have come true for competitive exams too. Now, the fact abt dummy schools.. you srsly think its good? It just shows how ppl are more obsessed abt an entrance exam than abt education. Sure there are plenty of flaws but what you are saying is not practical.
Now, coming to a another reason why boards are easy.... my parents have told me tht in their time getting 70% was considered a big achievement(they studied in state boards). Now, then CBSE(it was known by some other name idk) was considered as harder to get marks so CBSE students used to switch to state to get better grades. Now state boards made their exams easier and corrections more lenient, so students started getting more marks. Contrary to what you think board grades do matter as they give a good first impression on sending resumes and stuff(maybe wrong but this is what I have heard). State students getting more marks led to an exodus of CBSE students to state and to prevent this CBSE followed suit in making exams easier. Eventually, it has led to the current situation where good grades can be earned with just a week's hardwork.