It's no cheating, the PS4 version came just one year after it with the dlc, while it was still very hot, it was the same as a GOTY version. They are the very same game, and the PS4 version is the game legs it got taken away on the PS3.
It's not the same as a GOTY version. There's really no reason to double dip for a GOTY version, most people who bought the original game and liked it would have bought DLC as it came out anyway. GOTY versions are for new customers. But a remastered version on a new console? Now that encourages double dipping from people who enjoyed it already on PS3 and want to play it again on PS4.
If I played it less than one year ago I'll want to play it again on the PS4? That version was also aimed at people that did not play it.
The Last of Us was released on PS3 last year when PS4 was in sight and a version was announced short after. After the massive critical and popular success the game become a version with all content on a new platform (that turned to be vastly popular) was a no brainer for most people wanting to play it.
The PS4 version effectively stole the success legs from the game on PS3 and renewed its popularity, giving it a second wind, that last as long as the first should.
TLoU, as GTAV, was faded to a bigger success than the end of the console cycle they were released for could provide, and are games that keep selling a lot for half a decade (though on very diferent levels, as GTAV is a single tier beast).