While Ellis' decompression is at play here, it's not any kind of decompression I'd rail against.
The Planetary issues are decompression done right; they are light on plot but heavy on ideas and emotions, and the relative sparseness of the dialogue and simplicity of the plot(s) allow that emotion and those ideas to hit, and hit hard.
It has to be said, too, that what IS said is almost always perfect, and serves purpose an essential purpose. The Planetary issues have been boiled of all their fat; it's pure poetry of picture and word.
Every panel has some essential piece of information and the room to let Cassady & Martin (Depuy) render it. Nothing is wasted. Not so much is said, but a lot is put out there, giving you space to build deeper mythologies in your own mind. Exposition - of which there is much by the very nature of the series - is integrated into visually interesting mechanism/engine, and not just one but a number of very diverse approaches throughout. Bad/Average comics don't even try, but even quite solid comics often find obviously contrived / obtrusive ways to 'punch up' conversation ('training' is a big one in superhero comics). But because Ellis has to get a story told each issue, the exposition HAS to be embedded into the action of the plot. No extraneous or cheap nonsense.
I feel that everything Ellis tries to do in all of his work he accomplishes in Planetary. This is the platonic form of Ellis Comics.
Doesn't mean you'll like it (it certainly isn't my favorite series ever) but I think it's very, very good. And rarely do you see adventure/scifi comics done this well (indeed, I'm not sure it's been matched by anything outside of Moore's America's Best line, in that arena).
(I'm sure a load of people will come and correct me on that now)