That's a lot of good suggestions. I think the role-playing ones are the best, but those depend upon your players and their characters. I know that a number of my characters would want some of their equipment to go to their friends. ("May this shield defend you in battle as I will now be unable to. . . take the fight to the enemies of Pholtus for me. . . . ")
If item bloat becomes a problem, here are a few suggestions:
1. Sunder (and great sunder) for magic weapons. It's often a good tactic for bad guys and you can feel a little freer with using it when the party has extra wealth.
2. Exotic locations: Disarm a fighter on a rope bridge over a chasm and watch that sword dissappear. It's not sunder but adds a little more variety and spice to the combat--something that makes the rope bridge different from your standard 5' passage.
3. For consumable items, consider the following:
Alchemist's fire, acid, holy water. These pretty much have to be kept in brittle glass containers because otherwise they don't break on contact with the target (which is to say they don't work). A shatter spell will destroy all of these containers in a reasonably large area of effect unless the bearer makes a will save. Potions may be kept in metal vials which would be immune to this effect (but by default, they probably come in glass vials).
4. Scrolls would be highly susceptible to the shatter trick listed earlier if the character is carrying alchemist's fire
5. Scrolls will often also be vulnerable to water hazards. Dump a character in the drink and the scrolls he keeps ready to use at all times are probably toast.
6. Wands are a bit trickier but canny opponents will find that it's much easier to disarm or sunder a wand than it is to injure a well-prepared wizard with a sword. (Wizards often have ACs in the low 30's with Shield, Mage Armor, Cat's Grace, Protection from Evil, etc. but their attack bonusses are almost universally pathetic).
7. Warp wood can be a devastating spell against bows, spears, arrows, axes, and wands.
8. Black dragons of a certain age get an aura of pollution which ruins any potions that come near them.
Alternately, you could switch your death dealing tactics. Disintegrate leaves little wealth since most adventurers tend to wear their wealth. Death by fire elemental, the imprisonment spell, Remhorrazzes swallowing whole, etc. also stand a good chance of destroying items along with characters.