pir sayyid abdul qadir jilani said that in the hanafi madhab, it is makruh tahriman (prohibitively disliked) to recite suras in wrong order in salah. eg. it is makruh to recite alam tara kayfa in 1st rakah then recite wal 'asr in 2nd rakah knowingly.
so he said that in the time of rasulullah sallallahu 'alaihi wasallam the quran was not in this order of 114 suras. later on (i think the sahabas era) they arranged the suras in the order we have them today.
so, if it is makruh (i think where imam abu hanifa writes makruh it means tahriman) to recite quran backwards in salah, then it is wajib to avoid doing this.
so arranging the quran in this order was wajib and because it was not ordered by rasulullah sallallahu 'alaihi wasallam, then it is bidah wajiba (a necessary innovation).
btw...the quran as we have it today is exactly the same order as it is on the lawh e mahfuz.
so he said that in the time of rasulullah sallallahu 'alaihi wasallam the quran was not in this order of 114 suras. later on (i think the sahabas era) they arranged the suras in the order we have them today.
so, if it is makruh (i think where imam abu hanifa writes makruh it means tahriman) to recite quran backwards in salah, then it is wajib to avoid doing this.
so arranging the quran in this order was wajib and because it was not ordered by rasulullah sallallahu 'alaihi wasallam, then it is bidah wajiba (a necessary innovation).
btw...the quran as we have it today is exactly the same order as it is on the lawh e mahfuz.