Pumpkin pie is one of the few custard pies (or tarts) traditionally baked in a raw crust, i.e., a crust which wasn't previously blind-baked. A slightly soggy transition between crust and custard is both typical and traditional. Whether the style of baking was chosen for the result, or the result is an accidental artifact of the style of baking is anyone's guess.
You certainly could blind bake (or better, partially blind bake) the crust, then seal it before pouring in the pumpkin custard. Egg white is a typical sealant for savory dishes, but jams and jellies work better. There are a lot of choices which would mate well with pumpkin.
Since Chef Todd brought up the subject of technical crusts, you might have better luck with a pate sucree than a pate brisee. Everything else being equal, pate sucree crusts are crispier and don't get as soggy as pate brisee. Pasta frolla is pretty much the same thing as pate sucree. Both names ought to get you plenty of hits if you search. At any rate, I use a pate sucree, make the pumpkin custard with bourbon inter alia, and decorate the top with pecans.
Chef Todd is on the money in his disucssion of fat and its effect on flakiness/crumbliness. Larger, flatter pieces of fat make a flakier crust than smaller, rounder pieces which make for a more crumbly crust. The size of the fat pieces are an artifact of the type of fat used, it's temperature, and the technique and skill used to cut in.
There's no law requiring you to use a dough crust. You could make yours from crumb or even nuts. Both work well with custard pies and tarts. True, they're not exactly traditional. But, so what? Actually... they're both very fragile. You'd do better baking in a springform or a false-bottom tart pan than in a pie pan unless and until you get a really good handle on them. Again, no rule which says you can't serve pumpkin tart.
Speaking of tarts, you could use a pate sablee. It's a sort of shortbread crust -- very nice and very crumbly.