It's more to get people thinking about their spells. I'm using it to set the tone and establish magic is different. You don't just cast a spell, you need extra bits and components.
Ah, now if
that's your goal, I have an alternate suggestion:
Forget about limiting the Spell Component Pouch, or requiring the player to keep track of charges, or anything like that. Also, forget about the material components listed in the various spell descriptions (except for costly components and focuses).
Instead,
every spell requires a material component of some description, but that component can be anything vaguely related to the spell - you can cast
web with a bit of spider silk, or a bit of glue, or a preserved spider, or even some dead flies harvested from a spider's web. It doesn't really matter what, but it must be
something.
So, the PC Wizard has his Spell Component Pouch, and that's fine. But, when he casts his spells, the player needs to specify (as part of the action) what sort of component he uses. (You probably don't want to insist on the player declaring a component every time, because that would quickly get tedious. But maybe a couple of times per session would be good?)
The other suggestion I would make would be to dig out the "Power Components" rules - I think these first appeared in Dragon, and may have been repeated in "Unearthed Arcana". (Sorry, I can't give a more exact reference than that.) The idea here is that if the Wizard casts a spell with a specific "power component" he gets some bonus to the casting. So, if he casts
sleep, but instead of using a handful of sand instead uses a single pea taken from the matress of a princess, he affects an additional hit die of creatures.
By providing a modest bonus for using specific (but not hard-to-get or overly-expensive) components, you encourage the PCs to at least
consider it, and thus give more thought to their spell components. Of course, it does mean coming up with a bunch of power components and their effects... but my recommendation here is to cheat - allow only Wizards and Sorcerers to use them, and only come up with the components for those spells that they actually know!