I remember reading in many game magazines that it wasn't marketing that ended the Dreamcast, it was the guy that took over Sega.
He wanted out of making hardware and go to making games only and games for all systems. Because he felt Sega would make more money and supposedly he said Sega stunk at creating hardware.
Anyone who owns a Dreamcast would know that a lot of the of the games had graphics on par with the xbox and it blew away the Playstation 2.
Sony does too much marketing and most of their ads are just eye candy that make people say "gotta have it!!!". Then they go buy it and the game/system is complete crap. Except a small portion of games that are actually good