Well, I want to say I've outgrown mecha to some extent, except I still very much enjoy older mecha shows, so I'm pretty sure even with the nostalgia glasses on, it's more a case of meca has changed over the years.
First, I have to clarify that I was never a fan of the more classic mecha like Reideen, where it was thin on plot and big on robots beating up things. So, I'm not sure I'm really a pure mecha fan as this eliminates a whole host of classic and modern mecha from my appreciation list. I mean, I'm more than willing to turn my brain off and just enjoy shows mindlessly, but mindless beatem' ups tend not to hold my interest much. There needs to be other hooks in the absence of plot, whether it's beautiful women, lots of comedy, etc.
I've always been more of a plot-oriented mecha fan, and while my initial reaction is that we don't get much plot or character driven mecha these days, I admit it's easy to fall victim to nostalgia glasses. When I think back on the golden plot/character driven mecha, like Giant Robo (lol @ its remake), the UC Gundams (well, wasn't a fan of ZZ, but all the rest), Turn A Gundam (as an experimental steampunk mecha show), Aura Battle Dunbine, Ideon, Patlabor, Macross/Robotech etc, I have to remind myself that these shows didn't all come out at the same time, so I shouldn't begrudge modern mecha shows being so infrequent when it comes to plot.
That said, it's been slim pickings lately. Now, we have things like Stardriver, which I swear gets an award for the most well animated pile of empty calories ever created. If it wasn't for Macross Frontier, Eureka Seven (and, in all honesty, it took a very good overarching story for me to stomach Renton), and Xam'd, it'd seem like a dark past decade of mecha...to me, at least, and Macross Frontier is really borderline as to whether I consider it a mecha show. Lest I come across as overly critical, I had no real issues with Gundam Seed or 00, though I refuse to say anything good about Gundam Seed Destiny outside of lamenting that Athrun Zala is quite possibly the most under-appreciated Gundam character of all time.
It occurs to me that after I wrote all this that it's less the mecha genre I identify with and more the sci-fi genre, hence my disdain for many of the more brainless mecha out there. As such, I probably should revoke any pretensions of being a card-carrying mecha lover.
I admit, when I was a young child, being a huge Voltron fan though, so I can certainly understand why some enjoy those shows.
As for the general criticism that tends to be leveled at mecha shows, I honestly don't think the genre gets any more flak than any other genre. It may seem like things have heated up over the last decade, but that's more the move of social consciousness to the internet, where anonymity can drive many of us to be more critical than we are in 'real life'.
I don't mind people being critical, as long as they don't repeat themselves ad nauseam (ie: 10+ pages of saying "I hate this show" in a given show's thread here on these boards). I mean, there are about five posters in the Guilty Crown thread who keep writing posts longer than what I've just written here detailing how they love/hate the show, which is fine, until they keep repeating themselves as they talk past each other to the point that if you were to look at the last twenty or so pages, these people dominate 95% of the conversation; a conversation that can be summed up as "I hate Guilty Crown" "I don't think you should hate Guilty Crown". I feel like it's Thanksgiving dinner with the folks listening to the family go back and forth endlessly about the economy and politics. It's all so pointless after the first 30 seconds.
Stating your opinion once is enough.
I also am not terribly patient for those who criticize a show without having watched it, nor even done basic research into its premise. Otherwise, after reading any individual posters "I hate" post in a given show's thread, I generally just let the rest of their posts written in the same vein go in one ear and out the other. Life's too short to re-hash negative opinions in a constant, never-ending back and forth on an internet message board.
TL;DR Don't take it all so seriously and don't let yourself get sucked into a back and forth. Don't let those who consistently state the same negative opinion over and over again get you down, and concentrate on the things you enjoy, because if you end up posting more about how bad or not bad a show is more than once, then you're really no better than those negative nancies who are only filled with hate as an outlet for whatever is going on in real life that is stressing them out.
Edit: I voted the first option, but that's more due to a lack of the option "I love Mecha if it's plot/character driven!"