Making high-end cinematics is very, very costly. In addition, high-end cinematics do not enhance gameplay enjoyment, at least for the vast majority of users. For a great cost, there appears to be little in the way of return; yet they can, as the OP indicates, be used as a form of advertisement -- but for which target group? I think Stardock would be right on track by investing their budget in things in which they are specialists (e.g.: programming) and not things about which they have a proportionally smaller quantum of expertise (e.g.: cinematics; marketing) -- and for which, by they way, they would require external counselling and out-sourcing of expertise. Stardock's primary target group for this TBS will probably not include people who tend to purchase a product based on the aesthetic quality of a trailer cinematic. What's more, Stardock's main core competence is in programming -- they can afford to produce a game like Elemental (which due to its complexity and its probably lack of mainstream commonness and expectability fits an excellent "niche") without fear of ruining the company with suboptimal return-of-investment precisely because their stable earnings come from non-game products. Therefore: screw the opening videos.
I've seen maybe one person mention they wanted some tricked out trailer that would blow the minds of 13 year olds everywhere. As for me, and a few others I think, an in house trailer that can expand the awareness of the existence of a game outside the Stardock fanbase is all that is being requested. Because frankly, few people I play games with on a regular basis have ever heard of the company Stardock until I mentioned it to them and even then I had nothing to show them except some screen shots and a feature list for a game that was about as interesting to read as a spreadsheet. And before someone gets all postal on me about those kind of people not liking these kind of games, bs. They love Paradox titles and those are some pretty deep games and guess what, demos and trailers are released for their titles BEFORE the game is released. I've heard all the arguments for putting the glitz in after release but by then, our group has already purchased the games we've been demoing and following for months. And while Majesty 2 has some nice trailers, I think Europp 3 Rome only had some in game footage which was fine.