Re: the MegaCD, FAIL all the way through
There were some gems in there, that is true. Sega screwed up in not getting more games developed that took good advantage of the hardware. So many were just cartridge games with some FMV bits strapped on or just awful FMV exercises entirely. The people behind Battlecorps also did Soul Star, another showpiece for the hardware features.
The worst thing about the failure of the Sega CD was that it gave Nintendo a scare and caused them to cancel their very promising SNES-CD. This had much better specs and was intended to launch at $200 in the US at a time when the Sega-CD listed for $300. In addition to the much deeper palette of the SNES being far better for FMV, the CD add-on was going to have a FX Chip built in. This meant any developer could make use of the chip without having to worry about the expense or have a game with very low ROM usage to make up the cost. With CD it didn't matter how big your game was, the cost was the same. (Unless, of course, it needed more than one disc but that was usually limited to awful FMV games.)
There were two games ready to go at launch for the SNES-CD. Konami's Xexex was a Gradius-type shooter with polygonal objects. That one was never released in any form. And Square's Secret of Mana was an action RPG with FMV sequences. The FMV was removed so that the game could be released on cartridge and there are places in the game where it is really obvious something expository is missing.
If the SNES-CD had been launched as planned, it could have altered history quite a bit. 3D would have become a major game feature years earlier, and the N64 would probably have been CD based and more competitive, both in terms of software costs and developers already accustomed to working with polygons.