It is both good and bad. It allows delivery of critical fixes and new content, but it also decreases the demand for code quality from the start as well as increasing DLC. The bigger issue though is for the people who can't get it, like those whose only options for internet are dail up or satellite (with a 5GB per month limit). Sadly the market doesn't care about this small group enough to matter and we get left behind.
But, even with having a worse experience than a day 1 patch (that being unable to get the day 1 patch because it is 10GB and you only have 5GB for everything for a month), I wouldn't call it the worse thing ever to happen to game development.
Console games have survived for many, many years without the ability to issue critical fixes and they seemed to do ok. I've played console games since 1991 and I've never ran into a game that had bugs that made it unplayable. I think the QA cycle would be more complete if developers didn't rely on on-the-air patches.
It shouldn't really become acceptable to ship an knowingly subpar product with the attitude "we can always issue an update later."
There is an art in exploiting bugs in old games and working to glitch your way to worlds you aren't supposed to enter at that time. The kind of time and effort in finding these is really amazing. Finding and exploiting those bugs is an art form in itself. Take a look at this - https://www.youtube.com/watch?v=aq6pGJbd6Iw Skip to 12:15 for the real insanity.
But, even with having a worse experience than a day 1 patch (that being unable to get the day 1 patch because it is 10GB and you only have 5GB for everything for a month), I wouldn't call it the worse thing ever to happen to game development.