Those arguments are not convincing in the least bit.
By the time the PS4 actually rolls around, the drive and transfer speeds of blu-ray will be greatly improved. On top of that, you can always include small capacity flash storage to stream to from disc or hdd. That seems like a far more pragmatic solution than going with ssd as the game medium.
a 12x bluray drive would give you 432Mbit/s or 54Mb/s. Sandisk has announced a 16GB sdhc card that will do 30MB/s read. As I proposed. You can use a ssd case design about the size of the current 360 memory cards that can easily fit 4-8 sd cards or the flash chip inside those cards. That way you can scale up depending on needs. 2 16GB mods would give you 32GB of storage and 60MB/s transfer. 4 would give you 64GB and a 120MB/s transfer. Go with 8 of them and your at a 128GB and a 240MB/s transfer rate. You might say well who needs a 128GB of data next gen. Well it can be an option , you can allways go with 4-8 8GB dims. Giving 32-64GB of storage with a 240MB/s transfer rate. also while increasing the speed of bluray you may give up its constant read speed across the disc and seek times will allways be much higher than flash seek times.
Another option to reduce fees is to simply allow a kiosk where your bring your ssd card and can download the game there and max out the 240MB/s transfer rate. That be lets see 14.4 GB a minute ? Meaning you can download a 25 GB game in less than 2 minutes.
Ms can sell the ssd carts at $20 bucks and make a profit and then developers wont have to eat hte cost of the flash ram. They could actually decrease costs as they no longer have to ship a game , design packaging or anything else . At each toys'r us gamestops or best buy just give them a high speed connection and start streaming the game a few days early to the kiosks and have them act a peer to peer network to share bandwidth.
The stores can still take a cut of each download which can be less as the kiosk can be much smaller and take up much less games than current shelf space for games. It can actually be the demo unit for the system in question giving acess to hundreds of games to demo out at the store. The store can get a cut of the ssd cost also.
Then at home the users have a choice of storing the game on their hardrive (which may increase load times) or keep it on their ssd. Or they can buy multiple ssd cards. As the generation progresses ms can drop the price and phase out the smaller ssd cards. So for example you might be able to get a 32GB 4x8 card for $20 but at the end of the generation you may be able to get a 128GB card for $20. Couple that with a larger drive , perhaps go back to 3.5 inch drives as you no longer need a large optical device ni the console. You can now put in multi terabyte hardrives at a much lower cost than 2.5 inch or smaller drives. The drive can be used for movies , arcade games and demos . DLC can be kept with the game on the ssd .
You can also still do special edition of games. Just design a special ssd card with say gears of war 4 cog symbol on it , put in a figure , art book and something else and charge 20-30$ more for it than the one that is downloable.
BTW i use ssd card for lack of a better term.