The whole PS4 not playing all PS3 games and no PSN content is that Sony did not make a backwards compatible 2-in-1 like what they did the last 2 consoles.
the first PS3's had a hardware implementation of a ps2 inside it, enough to run ps2 games. the PS2 had a enough components of a PS1 inside to play PS1 games.
the later PS3's tried hybrid emulation, leaving only the GS and emulating the EE. that had compatibility problems and cost $$$ as the GS was still needed.
considering only a limited amount of PS2 games were released as PS2 Classics using 100% software emulation, its clear sony was not able to get 100% software emulation working very well.
BUT, sony left the ability to play PS1 games from disk even on all the PS3's, even the 40.
considering the PS3 has no memory card and Controller ports, Sony opted to map the DS3/Sixaxis to the PS1 Emulator as a DS1 and to use virtual memory cards (multiple even).
so Sony decided to cut all ps2 compatibility with the latest PS3s. (anything after the 20,60,80 fats,and the 40gb fat).
Microsoft did software emulation and it was not perfect but it got the job done, so they left it. although they could of bothered to release BC emu updates to fix some games.(*cough*MechAssault1,Crazy Taxi 3,ToeJam & Earl,Cel Damage*cough*). but they were able to do 100% software emulation so they lost 0$ allowing the slims to retain BC.
Sony PS Vita: everyone complained that sony should allow people to get their physical UMD's converted into a digital one to play on the Vita. same problem as the PS3/360, plus media differences.
the PSP part of the Vita is a PSP Emulator running on the Vita, and it doesnt emulate the Media Engine portion of the PSP, which is the reason PS Classics were not released and some psp games dont work, as without it, PS1 games have no sound and the PSP games that use it may malfunction. people who are running ARK/eCFW on the PSP emu know this as PS1 games play with no sound. Sony decided to handle PS1 sound emulation for the released PS1 Classics using a native PS Vita PS1 emu vs updating the PSP Emulator to emulate the Media Engine. Sony did however use some sort of Wireless Wrapper to allow PSP games to use the WPA2 Wireless N wireless the Vita featured. PSP could only do wireless B/WPA1.
As for the "should Wii->Wii U VC upgrades be free", well, PS1 classics are free to redownload on the PS Vita and they use a Vita Mode PS1 emu as a workaround for the lack of Media Engine emulation on the PSP Emu. that costs $$$ too.
so if Sony is doing it for free, why should Nintendo not be?
NDS/L: could play GBA games but not GBC nor did it have a link port. People got over it eventually, ran goomba/lameboy, OR JUST used their GBA TO PLAY gba games on.
GBA: could not trade pokemon from BGR/GSC to the GBA games. link cable pinout was different also, cound not be used as a GBC link cable without modification. people got over it and left their old pokemon behind.
GBASP: requires a headphone adapter cable for headphones, people got over it and got one, or used a regular GBA.
GBA Micro:Could play GBA games but not GBC, it had a link port but was smaller and needed a different cable to plug into other GBA's, people got over it and either stuck to a GBA/SP or goomba.
DSi: No GBA support at all. no way to transfer pokemon from RSE/FRLG as there was no GBA slot nor hardware to do so. people got over it and used DS Lites/fats for transfers or GBA games. or emulated them via the DSTwo. also failed to allow DS games to use the WPA and wireless G features of the DSi wireless card via some sort of wrapper like how the Vita can for PSP games.DS games still need to connect to a Wireless B network.
3DS: was able to play emulated GBA eShop releases (only 20 and for Ambassadors only too), people got over that quickly, as its Nintendo.
the DSi features were retained in the 3DS-some preloaded apps. also failed to allow DS games to use the WPA and Wireless features of the 3DS wireless card via some sort of wrapper like how the Vita can for PSP games. DS games still need to connect to a wireless B network.
GameCube: oh noes!11!, it cant play my N64 game carts. well, the SNES and N64 had no BC either. people got over it and played GC games.
Wii: retains "Most" of the gamecube minus some small things like the broadband adapter, or the GBA PLAYER. people were fine with that. the Wii was Wireless only (usb lan adapter extra and not included) so no broadband adapter wrappers for the USB lan adapter were ever added to the Wii's "GC Mode".
Wii Horizontal Revision: NO GC Support at all. still could play Wii games that did not require GC accessories. who needs Wavebirds for Brawl,Mario Kart, or the ability to play Melee anyway?/sarcasm
Wii Mini: a DoorStep, nuff said. what use is a console you cant even play Skyward Sword on without having to worry about the Save Game bug as you cant download or apply the fix to it via another Wii with no Internet or SD card slot to do so. Nintendo could of at least Pre-Installed the save updater. talk about carelessness.
Wii U: No GameCube (Nintendo plans to release GC VC titles tho later on), can play Wii games along with eShop titles/VC via WiiMode(which refuses to launch if the Wii U detects a system update), but they cant utilize the Pro Controller even tho its Bluetooth like a WiiMote. they did however do the wireless partially right, WiiMode can use Wireless N when the Wii only had B/G, but cannot use WPA2 like how the DSi/3DS could not for DS games.
NO GAMECUBE:if Nintendo can emulate the GameCube enough to make VC titles then why not allow playing GC games from disk via a GameCube emulator same as the PS3 can with PS1 even if its not all games? (The PS1 emulator cannot play all games either)
the pattern i see here is that people got over any BC related things Nintendo did/did not do ,
and then bash on Sony/Microsoft when they lack BC.
and once the Wii U gets older, whats going to stop Nintendo from ripping out Wii disk compatibility (or even WiiMode) on later consoles leaving you with no way to play Wii Games or no way to use any Wii titles if WiiMode was removed. they can and may if it will save them enough money not needing to put Wii components into the Wii U.
they did to the Wii with GameCube support. how much does anyone really think they saved removing the ports and some resisters, not any, it was the drive. using a 12cm only disk optical loader was cheaper and less complex as it did not need to accept 2 disk sizes. since Wii U games uses Blu-Ray like disks, they could save money using a drive that does not contain both a 640nm(DVD) and a 405nm(Blu-Ray) laser.
