I can understand why people are upset by this ret-con of Grace's character. It goes against what we've known and learnt about her over the original series' run and the past season or so. But I agree with @Chicken Wing in that just because we never knew this about Grace doesn't mean it couldn't have happened. Do we wish it was addressed years ago? Well, I can't speak for you guys, but I am glad it wasn't. W&G is a sitcom. It's meant to be kept light-hearted, though I never laugh along with the audience. I watch it as more of a light-hearted drama, not heavy drama that we expect from shows such as Special Victims Unit.
What really bothers me about this whole rehashing of Will & Grace is that the show ended twelve or thirteen years ago (I know three of my favorite sit-coms ended three consecutive years: 2004, 2005, 2006. Always got W&G and ELR mixed up!) and we got our closure with these characters. Was I happy with the series finale? Hell, no. I wanted Will and Grace to start a modern family type of thing with Lila. I didn't want Grace to go back to Leo, that cheating douchebag. But she did and it ended that way.
When the show returned, they ret-conned all of season eight. No Lila, no pregnancy, no Vince or Leo. Just all these characters, now in their late 40s or early 50s, behaving just how they did twenty years ago. I can definitely see why the creators and EPs of another popular show from the 90s refuse to do a reunion movie or revive the series. Looking at this show, it's like... just doesn't sit well. It's too modern, but these characters behave like they did twenty years ago.
But back to the topic of this thread, I liked the Grace storyline despite it being an out-of-the-blue ret-con. Wasn't very fond of Will, Jack, and Karen plot. I think Will is extremely weak with Jack and Karen, and is strongest with Grace. The same can be said of Eric and Debra, I don't know what it is but they have amazing chemistry.