Value for money
Considering the cost of making a movie that is 'Episode seven' or 'Big Tough Bloke 5' then I guess that many people realise that the constant re-hashing of simple themes and then releasing what amounts to a poor follow up (ups) come a very poor second to the huge budget non- movie series.
The popularity of made for telly/net progs like Games of Thrones (no, I haven't - I read all Martin;s Space Opera stuff years ago and can't see anything really any different this time) ties audiences in to a regular spend and the ability to watch whenever and wherever they like.
Given the choice of a local sweatbox (or freezer) with leaky sound and dickheads with phones as opposed to getting some beers in and skinning up a couple in readiness, folks will prefer to stay at home (or visit a mate) and watch on a big screen with a good sound system instead.
There are many movies that are 'BIG' visual productions but they easily lose thier attraction after the fourth huge orange explosion accompanied with CGI debris that comes right at you.
Me, I'm about to spend out on the South Park game which will last a lot longer than 1:45 for not much more of an outlay.