I've seen a few articles online suggesting that BR's biggest fault was that its budget was out of line with its potential draw. It is a niche sequel to a niche movie that itself failed at the box office. It relied on nostalgia and and the awesome trailer visuals to fill seats, which apparently were not enough.
The same could be said for the Tron sequel, (which i liked and hoped for a 3rd film) A bet was made as to its box office draw because of its Cult status.
Hollywood is stuck in a mode right now of mostly making movies based off of recognized brands and not venturing towards the gamble of a new IP. Retro is in Vogue right now and cult films have an established fan base to build upon.
But Tron like Blade Runner do not appeal to a wide audience like you say, and when you have a bloated production budget (which these films NEED) a huge gamble is taken.
I wonder if we are witnessing the end of huge budget Science fiction films. If you look at films like Tron 2, Blade Runner 2, Alien Covenant they all had large production budgets, and even though they made a profit they still
under performed and thats the key phrase
'under performance'. They where given a budget based upon their assumed potential success. Expectations where made as to the movies profitability and it didnt matter that a profit of say 20 million was made.. Its not proportional to the 190 million production investment. it fell short of expectations so the well is considered dry for that IP.
The movie Arrival (another film directed by Denis Villeneuve) was considered a success both critically and financially because it only cost 40 million to make and made over 170 world wide. Which i am actually glad of, because i really miss thoughtful intelligent science fiction at the box office.
The mind set exists that Sci-Fi movies need to be expensive and special FX driven, which often lead to a Science fiction film underperforming or being dumbed down to appeal to a broader market.
Personally i'd like to see Sci-fi become more thoughtful, intelligent and produced on an average budget.