There is no such thing as perfect capacity. Most attractions are either over or under engineered and both present issues that need to be managed (as they are doing with Rise). WDI picked a perfect ride system(s) to tell their story, generate demand, and maintain relevance for their audience.
There may not be such a thing as perfect capacity -- but there is such a thing as
adequate capacity. Given Disney's prior decisions to add an additional track to Toy Story Midway Mania, and create a duplicate Dumbo ride (the latter of which didn't change the ride system in any way, but simply made another copy of it), it's not like this was a new issue for the company. RoTR's lack of capacity is an issue that Disney could have anticipated (e.g., touted as Disney's biggest and best attraction ever, with commercials airing every 5 minutes to draw people to come see it, but with half the capacity of it's a small world!?) and solved long ago.
While forcing guests to scan (and potentially waste) a park ticket just to enter the park, where they'll have the
chance to compete for the
chance to ride RoTR may be the best way Disney can think of handle the crowds at present, it doesn't change the unfairness of the situation for those guests. Every day, dozens if not hundreds will lose out on the opportunity they've waited months for (and spent thousands of dollars to build a trip around), even though they did everything they were "supposed" to do to get into a boarding group. This is the first and only Disney attraction I can think of, in my lifetime, where this has been the case -- where no amount of time, money, preparedness or willingness to arrive early can possibly guarantee you a spot in line, and where you're nonetheless required to sacrifice a day's admission and precious rope drop time you could have spent elsewhere, just for the privilege of finding out whether you're one of the lucky ones. If that's not the result of of woefully inadequate capacity - something for which Disney has no one to blame but itself - what is it?