The best use I can see for them is as a staging point. Say you have to jump to another system (far away). If you jumped straight to an enemy planet then your AM reserves are going to be low from the long phase-jump. you could instead jump to the star first, rapidly recharge your AM, and then make the relatively short jump to an enemy planet.
just look at how far into a system the sun is. unless if you're galaxy is right over (or near to) their star that won't be very usefull.
When they arrive their ships will still be low on AM from the previous battle (their recharge was much slower) and from the jump to the new location.
keep in mind the "exhaustion" of your engines from phasejumping. you don't just lose AM, you lose capacity for AM to.
speaking of planets: I want to see colliding solar systems.
I know its unrealistic in both chance and gameplay but...