Most of the time it's a very bad sign, but for Titanfall、I'm in doubt of that. There were a beta, and also I don't think even with an embargo such hyped game could be very bad without anyone leaking this information.
It sure could below expectations, but to some extend, most hyped games are. In this case they didn't show crazy fake graphics, or extremely innovative new concepts that could be lies, so it could even be better than expected and they just want to build the hype.
Anyway I think that's very wrong as a business practice. It means they ask their clients to buy their game without a good knowledge of its quality, size, depth, balance. Without the leak about maps, clients don't even know if there is enough map to have fun, or if they are to buy lots of DLC to have a good experience. For the company to have assurance the game will sell well at first or have a better hype after release thanks to the embargo, they are stealing the client assurance that the game is good or as expected. I think it's very unfair.