I guess that something as easily obtained as resources should always be viable and never have the chance to decay or lose any amount of value.
Easily?! Easily?! First question what crafters do you have Goldberg and how often do you use them? I made most of my GM crafters in the very old days by by double clicking and picking my options from an unwieldy menu, one at a time, no make last option, no make this number, no UOA macros - so it wasn't easy. But the past is the past, while you're right in that it's not hard to swing an axe and get some lumber, think of this scenario.
A guild member just placed a new house and would like some furniture made out of heartwood. Being a fine upstanding guildmember you pick up your axe and head out to get some heartwood logs, looking at the furniture the guildie wants you know you need about 1000 heartwood boards. No problem, first tree...normal boards..well those are gonna expire so might as well leave em on the ground, or I could gamble and try and make something that someone might eventually want. Next tree...Frostwood!! That's awesome., but oh wait, I have no use for frostwood at the moment and I have no vendor..damn...might as well move on the next tree...and so on and so on until you find your heartwood tree. Now all the wood I have chopped down while trying to find my heartwood tree has to be sold or used in 2 weeks or I'm screwed?! Hmm, next time here's what I'll do...find a vendor who clearly scripts, or go to one of those websites and pay real money for duped resources. How does this help UO?
And the idea that this promotes active healthy play, well by that extension we should make everything decay including skills. I can see it now, you log out your legendary tamer, go on a real life vacation, come back and you're down to an Elder Tamer. No problem there, you say, it's fun and healthy for the game to go out and train this back up...no thanks, I'd rather just make myself a full-size hamster wheel and run in circles...now that would be healthy!
The only good that can come of this discussion is the hope that a bad idea spawns a discussion that leads to good ideas. Having said that, your idea is bad and even the most out-of-touch Dev wouldn't implement this idea on their worst/last day at work. Look at how people are whining about cursed and brittle items (which I actually use) and you want them to do this now? Here's a different approach, find a way to make resource gathering fun (wouldn't be hard, but would take up dev time), and make scripting harder and less rewarding. Problem solved.