From a gamer's point of view, it's more than easy to suggest many different approaches to implementing a demo, one more fascinating than the other. However, from the programmer's and/or developer's POV, not having included a demo in the design process can often mean that being forced to try to come up with a viable, working solution for it later on, when the game is nearly finished and ready for release technically speaking, can be a real pain that a common gamer can probably never truly appreciate.
Many commercial games also do away with just trailers and are being purchased nevertheless, because beta testing ensured that the declared system specs the game requires will work for all potential gamers in 99% of all the possible situations, unless something unexpected goes really horribly wrong. I would say just bear with it and try to show the devs some respect by exercising patience.
Lukas
I won't be using this account any more or participating in the forum activity through other childish means like creating an alternate account. I've asked for the account to be removed but I'm not sure if that's actually technically possible here. Just writing this for people to know that I won't be replying, posting new topics or checking private messages until the account is potentially removed.