They should stop spamming influence stations everywhere (Carnoids are the biggest offenders), it's very annoying. I'm not too fond of them capturing resources too much either to be honest, it just makes me want to kill them off even more.
Their constructor building is way out of control, they tend to build constructors and freighters and maybe a handful of horribly underpowered attack ships (3-10 ATK point ships when they have much better tech available).
Personally I try to keep the minors in my sphere of influence alive because they make good trade partners and you they are good for econ/research treaties, I'm sure it's more profitable to just kill them for their sweet sweet homeworlds though.
All the minors really need is to be somewhat interested in not dying, I really don't expect them to have amazing AI or anything, just good trade partners, and perhaps build a few military bases around their homeworld + keep a small but fairly well armed navy going.. they seem to have zero interest in defending themselves, they put 8 constructors in orbit of their homeworld, spam worthless influence stations now and then, and wait for death.. considering they all have PQ 15 base homeworlds they are already tempting enough to kill off. =P
I wouldn't also mind seeing some new minor portraits.. like 3 of them are tied to that 'froggyman' portrait for some reason. More variety would be nice, maybe add some good player submitted ones? The ability to create minors (without having to go XML editting or what not) would be cool.