According to me, it is a good move. You can copy and paste the pnr from chat or mail. That is an advantage.
Plus, When try to check pnr status at indianrail.gov.in, after filling in first three digits, if you don't continuous type the next 7 digits, you get a dialog "Please enter valid pnr". (in case you go to another tab like mail/chat to check the rest of the pnr). This is very irritating. Also when accessing from mobile, after you enter the first edit box, separate loading happens. That won't happen if it is a single box.