With large volume flash storage becoming cheap, far in excess of that of DVD and even bluray, why not use them as game storage.
Because mass produced pressed discs are still cheaper to manufacture than flash storage. a 32GB SD card costs 20 bucks, a 50GB blu-ray RW disc is 3.50
Games could be saved onto the flash drive, the hard drive or both,
Where have you been the past 9 years. You can, if you want, go digital and install games from PSN to a PS3 hard drive and never bother with a disc. On the PS4, games are installed to the hard drive, even if you use the disc. (if you buy the disc version the game will do a disc check on start but that's all you need it for)
The PS vita, uses a combination of pre-loaded games on cards, and games downloaded to it's storage.
They're not fragile, not if you take proper care of them. I've got 19 year old PSone CD's, DVD's and Blu-rays are even tougher.
and the space used for the optical drive can be re-purposed for proper cooling equipment that "modern" consoles clearly require.
The PS2 had a fan, the PS3 had a fan, the PS4, has a fan. They HAVE proper cooling, where have you been the past decade?
Console manufacturers missed the boat with this generation so console peasants will have to wait 4 or 5 years to get this.
Elitist PC Gamer Burgeosie are so out of touch they don't realize that they really don't know what's going on with consoles.