I agree. My character's AC currently stinks, his HP are atrocious, and his bow being sundered will be the last problem he has if something gets to melee on him.
Though I don't have to worry about magical (or even masterwork) arrows because of metaphysical weapon (my third level power), cover will prove a problem until I get my sharp shooter feat to start negating cover. The Deepwood Sniper class already negates some concealment for me.
Bad weather can be a bother, but keep in mind, a highly min/max'd magical archer is more like a sniper than a true archer. Archer's do not have magical bows and arrows, superhuman aim and vision, nor magical items that enhance their already superhuman abilities. They have to make do with human abilities.
A rainy day will stop an archer (or at least severely hinder him) it will not stop the streaking silver missiles of a sniper (though it will hinder him).
You have a very strong point with magic, but of course magic can be used to stop just about everything. Melee, other magic, ranged attacks, natural attacks, magic is extremely versatile both in offensive and defensive capacities. Is this a unique weakness of the archer? I don't think so. I could be wrong, I think a prepared mage is just about the most dangerous thing in D&D.
But an archer, especially mine, is very well equipped to deal with a mage. First off, my particular archer has a spot check of +28. By the time he reaches his 8th level of deepwood sniper he should be up to +42 or so.. Assuming I can't talk our artificer (PC with item creation feats, he usually ends up with all our money.

) into creating some kind of item like a ring of jumping that affects my vision instead.. Then it'll be more like +62-+72...
I'll also hopefully have a bow of distance by then that with my far shot feat, and my deepwood sniper range increment increases should allow me to (and forgive me, I have none of my books with me at the moment) hit a target at 110*1.5*2 + 70? = 400 ft? Something like that, probably less, but the point is, a bow can shoot up to 10 range increments away with a -2 per range increment. If I can use my vision to pick out a target, and hit him with one of those 390 damage crits at range, especially if I'm hunting the guy and it's the first he knows of me, I may kill him with one shot before he gets that magic up.
Then again, all things considered, maybe not. But at least the archer still has a better than average chance.
