Pool mining would really be a nice and convenient feature in GUI. However, I do agree with xmr-eric's comment on there:
Suddenly pool operators have an incentive to get in good graces with XMR devs? Already we can see MoneroWorld (where I personally mine, so I love it there) is at the top of the list?
What if one of the listed pools gets hacked, malware, or leaks private data? Are we partly responsible / could be sued? We have to wait for a whole release before we can change the code away from an adversarial pool?
This is not decentralized, and thus sort of goes against the spirit of The Monero Project.
I'm a big fan of adding a solo smart miner to the wallet. Not a fan of this.
Indeed, The Monero Project should not get itself mired in pool or market politics. Besides, there are already a multitude of pool mining guides out there.
A solo mining feature in GUI is totally fine as it is at the core of the decentralized nature of Monero and most if not all of the other cryptocurrencies. Besides, who doesn't want to participate in a lottery anyway and made easy at that?