Plain and simple it's just arrogance. Disney figured we'd be happy just for the opportunity to walk into a star wars land. And then even happier to spend $200 to build a lightsaber, $100 to build a droid and $50 on drinks in the cantina.
It really does depend which angle you look at it from imho. I'm quite a pragmatic person and for me the way Disney has opened it is completely fine. Originally it was scheduled to open 'in the fall' (?) and I assume when originally planned, it was to open with both rides operational. We'd booked our 2 weeks starting September 11th way back in December to coincide with Halloween Horror Nights and at that stage assumed that GE wouldn't be open.
When Disney announced that they were opening GE earlier than planned on 29th August, I couldn't believe our luck. The amount of times I read complaints on here about how long it takes Disney to build and open rides you'd be forgiven for thinking that people were getting what many asked for, something opening earlier than planned. It would have been great had both attractions been ready upon opening early, however with the infrastructure and one attraction ready early and the other one not, that wasn't possible.
So Disney had a choice. Open earlier than planned making it as clear as possible that there's just the one attraction available upon opening, or keep a land that's 75% functional closed for a few months until both attractions are ready. For a visitor this should be quite a simple decision, do I go now with one attraction open or do I wait a few months and go with both open. I'm going now fully aware that the 'better' attraction isn't yet open, I'm going aware that the fully immersive feeling may not be there as much as if both rides were available. Nobody is making me go as I could decide to wait till next year's visit and get the 'full deal', but as a pragmatic person I've weighed it up and decided that something is better than nothing and that I want to see it now.
I'm fully expecting that when we go next year that I'll almost certainly enjoy the GE experience more, as there'll be more to do. But again, I'm going in knowing this to be the case and nobody is forcing me to go in now so it's really all on me. Now there will be some folk who unfortunately go not knowing that one ride isn't yet open and that's a real shame. I do think however that Disney has done a lot to publicise the fact that ROTR won't be open, I think most people would agree on this.
As for people being 'even happier to spend $200 to build a lightsaber, $100 to build a droid and $50 on drinks in the cantina', well that's their choice. You pay before you enter and if you book in advance you have to provide credit card details, so those doing this must by default be happy doing so. I'm doing none of those activities because I don't consider them important enough to spend that much money on them, I'm quite happy not to do them and make that choice. And from all the videos I've seen about building light sabers, the people participating seem extremely happy to be there and appear to be having fun making them. I suppose time will tell how long people will be willing to pay these prices for these experiences but from our group of 5 going this year, 2 are doing it and are very, very happy about the prospect.