doctor who - Why didn't Daleks simply destroy Satellite Five?

1. Satellite Five was shielded.

True, Jack and the Doctor had concentrated the shielding at the top six levels, but that doesn't mean the rest of the satellite was unprotected. The Daleks were able to infiltrate it with an attack force, but being able to actually blast through it might have taken more energy than they were willing to expend. Possibly the same reason they sent Daleks down to Earth instead of just blasting away at it from space.

From the transcript:

JACK: We've now got a forcefield so they can't blast us out of the sky, but that doesn't stop the Daleks from physically invading.

PAVALE: Do they know about the Delta Wave?

JACK: They'll have worked it out at the same time. So, they want to stop the Doctor. That means they've got to get to this level, five hundred. Now, I can concentrate the extrapolator around the top six levels, five hundred to four nine five. So they'll penetrate the station below that at level four nine four and fight their way up.

2. They didn't know what the Doctor was planning at first.

Simply blowing up the station might have triggered something they weren't prepared for. The Daleks have always exercised a certain amount of caution when dealing with the Doctor because they're never quite sure which was he's going to jump, and so they don't want to commit themselves to any one course until they can be sure of his intentions.

Of course, as @SachinShekhar and the transcript above points out, they do figure it out, but by that time, Jack and the Doctor have the forcefield in place, and the Daleks are still too far out of weapons range at that point anyway.

3. Hubris

Stemming first from their creator, Davros, and reinforced by the religious zealotry and insanity of the Emperor, this particular strain of Dalek thinks of themselves as invincible and instruments of divine retribution. The impersonal destruction of humanity from space is too cold for them; they need the up-close kill, to look their enemy in the face as they are defeated. (Another reason to send Daleks down to Earth instead of using the ships.) Also, the Emperor would specifically want to see the Doctor die before it, to know the moment of his defeat intimately.