This has been discussed several times in the past.....true RPOs would basically require a full, ground-up AI rewrite, and thus aren't likely any time soon.
EA devs have talked publicly about this. What you described as "easy to implement" is purely from a user control perspective...AI is an entirely different critter.
The run block/pass block decision is a keystone AI trigger for (nearly) every other AI behavior; defensive player behavior especially is based on it. If simply dropped in as is, you'd get behavior like DBs simply freaking out and ignoring routes. Failed handoffs, the o line simply failing to move, receivers freaking out, etc. Draws work because nobody is going downfield to block first, and as it is, draws can cause some really weird AI behavior. A downfield route while the line is run blocking is straight out.
Those dependencies can be changed....but there are so many, you're 75% of the way to a full AI rewrite anyway, and you probably better do it to avoid some ridiculous code regressions.
And for the record, no, NCAA didn't have RPOs. They had some play-action plays where you could force a handoff instead. RPOs were in development on the NCAA engine (that was traditionally where EA did most of their new stuff), but it wasn't ready for NCAA 14, and the series was cancelled after that.
Some quick source articles....the SB Nation one in particular is a great read, and a strong example why EA needs to bring NCAA back, to improve Madden's quality if nothing else:
https://www.sbnation.com/college-foo...ootball-madden
https://www.usgamer.net/articles/mad...ss-option-news