I never purchased a game that required whatever its called but why was it so heinous?
It was basically a completely unnecessary service from the start, Microsoft originally tried to charge PC players to use it ala Xbox Live on the 360, so if you bought a GFWL game on Steam or any other service, you'd start the game, in that service, then you'd have to get your code and put it into GFWL to activate the game. So basically it was like having Steam plus a crappy version of steam on every GFWL title. GFWL servers are shit, by the way, so games like Dark Souls, whatever Bioshock 2's multiplayer, whatever, all had to use GFWL rather than integrating Steamworks and Steams' multiplayer server infrastructure. And GFWL is easily hacked and has never had any support from Microsoft to police or ban hackers in any way. GFWL was a service Microsoft started thinking they could suck a subscription fee out of PC gamers to have, when they rebelled against it, Microsoft left it running and went out and recruited games to sell on the service and to utilize the service, but gave it zero support in any way from then on.
Then you have as mentioned above that game saves would be deleted by it (never happened to me but happened to lots of others) and now the fact that the service will be shut down completely, which will probably mean Dark Souls on my Steam account is no longer playable online after next year, you know, a shit load of people bought games through that service because, for instance, Grand Theft Auto 4 was GFWL integrated, so that impacts them as well.
On the topic of GTA 4, if you bought it on Steam, and then bought Episodes from Liberty City on Steam, you could never run them through the same client, because you couldn't activate EFLC on GFWL properly in GTA 4, rather you had to use an entirely separate install, its still that way today.
GFWL was absolutely shit in every way, the only problem with it shutting down is that its been up so long if you play PC games you probably have some titles on that service and now you're fucked out of those games.
This conclusion to this saga was foretold the moment GFWL was announced.