Good/bad writing is the least of anime's problems.
Far from it, in fact. While much can be argued in support of animation, sound, or character art, good writing can carry a show farther than technical wizardry or raw moe appeal can. I say "can," because quite often the popularity or marketability of a show or its characters will eclipse any need for such luxuries as a coherent plot, captivating story, or compelling characters. Still, the quality of writing of a series or work can often mean the difference between a pretentious money-maker and something for the ages. Poor writing was what kept Code Geass R2 from being anywhere near as good as the first, and good writing was what made Persona 3 such a damn fine game.
In my opinion, to make another season is a gamble that should be taken. When I find a good plot-driven show that only has 12 or 13 episodes, it's like, "Why bother?"
Hm. Interesting. It is often a gamble to make a second season, especially when the first was received so well, as the fanbase can turn quickly if provoked. K-ON faces no such uphill battle, from what I can see, as it will likely make the money back with room to spare based on its sheer moe appeal, DVD sales, and merch. Now, making a second season to Darker than Black; that was risky. Given how well it was received by audiences on both sides of the Pacific, the second season was held to a fairly high standard indeed and seems to be meeting it. Welcome news, given the general lack of marketability.
As I said before, the length of a series can directly impact the nature of it writing. Baccano! works better as a 13-ep anime because of how the studio chose to adapt the corresponding sections of the light novel series. You
might call its ending premature or forced, but it is not made up out of whole-cloth as too often hits series like Claymore. Baccano! ended before it got a chance to drag its feet, so to speak. Black Lagoon's first season fits here too. Why bother with something so short? Because it can be very sweet indeed.
Even if it's "good," it probably won't be enjoyable;
A common misconception. The quality of a series and its entertainment value are not mutually exclusive and can complement each other (as in Baccano! or xxxHolic). However, there are times when this maxim can be perceived as true (Mushishi), or reversed (Hayate). And sometimes, it's neither (Seitokai, Zero).
Also, you text-bit Meg; that's kinda creepy.
*sigh* Dispatched, in mankind's darkest hour, we are Knights of the Blue Flame.
けー… 我々は, 終末の日に遣わされた白日の使徒にして, 蒼炎の騎士だ。