Class 12 marks of any board will not be considered in JEE Mains ranking from this year, that is 2018.

Is that a good step? Read this paragraph first and then lets analyzing the decision.

Hope you are aware that the 12th Marks won’t have any weightage and will not be considered in calculating the JEE Main ranks 2018.
The only importance of the 12th board exam will be that you must have secured at least 75% marks or be in top 20 percentile of the board you appeared.
For Sc/ST, min marks percentage is 65%.

So first of all, class 12 board exam is not redundant yet. Since one must secure 75% or be in top 20 percentile to be considered for JEE Main Ranking system.

The CBSE board is cutting the syllabus from Grade 1 to 12 starting from 2019. Maybe, they are unsure of the curriculum yet. Hence it makes sense to not consider the marks yet take the cream students. Also if they do cut the syllabus by 50%, I wonder if the CBSE students will be able to prepare well for JEE by depending on only the course material? JEE will definitely not lower the standards of the exams.

So, it also means that the CBSE students may find it difficult to cope up with the JEE entrance exam which they used to manage by preparing for their Board exams till 2018. Another situation that will occur soon is that since the CBSE classes will have a lesser syllabus to cover for boards, they will have more time to prepare for the entrance exams. They will benefit two-fold.

Time for ICSE and other boards to make quick adaptation before the exodus to CBSE schools starts again.

source: https://jeemain.nic.in/