Well, way back then, the only way to see a movie was in theatres. I guess in the 70s watching it on network TV was an option, but there would of course be commercial breaks there, so the theatres were still the optimal option. Nowadays with home media being where movies truly live, the theatres have to have more publicity and more upfront gratification in order to be perceived as worthwhile.
With Network TV --- wasn't there usually a TWO to THREE YEAR delay? Even more than the commercials you mentioned, that whole delay could kill interest.
Also, especially with the Star Wars example -- Blockbuster hadn't even been born yet, and cable TV was still in its infancy. The only "other" option would be the Dollar /2nd Run Theater, which would be a more affordable way to see a newer movie.
And yo are quite right -- you need more of a reason to go to the movies nowadays.
Star Wars was an unknown property from a director whose only previous success has been American Grafitti, a coming-of-age period piece, and the only big names in its cast were Alec Guinness and Peter Cushing.
I've been saying for a while now, the industry has gotten too obsessed with advance buzz and first-weekend results. It used to be that an unknown film could build an audience by being good enough to generate positive word of mouth and repeat viewing. It used to be a simple formula: make a good movie and people will see it. These days, everyone's gaming the system and talking about ways to give a film an edge with a big name or a known property or whatever, and it's all about handicapping the horse race rather than telling good stories.
You
do realize that your example is nearly
50 years old -- two FULL generations ago! And we mentioned the landscape then as opposed to now. There also seems to be
many more
new movies being released, in addition to the ways they can be seen.
And most of us have neither the time nor the resources to see several movies in the theater.... many of us are more picky. In addition to our social circles... box office just about the only way most of us use as an outside measure to consider a movie.
Why watch a movie people don't seem to like?
And
more important, at least for those who you expect to actually
make the movie: why spend money on a movie when you can't make your money back, let alone make a profit?
That may not sound right or fair...but life , especially now, ain't fair.