The habit of searching everywhere is, to some degree, the fault of game developers hiding useful (and sometimes critical) items in places that can't be revisited. (Examples of this include early Sierra adventure games (where missing an item can make the game unwinnable) and PSX-era Final Fantasy games (where missing an item might prevent you from getting a character's ultimate weapon).) If developers hadn't done that, I think you would see fewer players going out of their way to explore everywhere and get everything before continuing on.
A related issue, and one that bothers me, is the tendency to find all sorts of rare consumables and never use them. It's a habit I want to break, but unfortunately, games often don't make the habit worth breaking. (I find this easiest to handle on a repeat playthrough, as I know what the trouble spots are and when it's worth using an item there, without fear that I'll need it later on.)
The thing is, consumable items you find fall into three categories:
1. Items that are common, typically available in unlimited supply.
2. Items that are rare and powerful and useful in the harder parts of the game.
3. Items that are rare, but not powerful enough to justify their rarity.
The problem comes in that some games have too many items that fit into the third category. You see this in some Final Fantasy games (2, 3, 4, 7 (attack items), and 6 (why use X-Ethers, of which there are only *3* in the entire game, when you can farm Elixirs, which are strictly better)), and it just makes those items feel pointless. The problem isn't just restricted to JRPGs; Dragon Wars has items of this type, including most types of arrows (you can only buy basic arrows, and except for a certain magical quiver with unlimited ammo, the arrows you find aren't strong enough to justify their rarity). Games with weapon durability and no easy way to repair weapons can suffer from this issue as well (SaGa 2's original version, for example; maybe some Fire Emblem games? Also artifacts in Daggerfall with magic repair disabled (which is the default).).
IwubCheeze: Edit: I had to restart Resident Evil Revelations from the beginning because i didn't explore enough for weapon mods. I couldn't beat the end boss because of it.
Couldn't you have just gone back to earlier areas and explore the areas you skipped? (If the answer is no, then the game is flawed in the way I just mentioned, and that game is just another that contributes to this habit of players.)
Edit: With that classification of consumable items, who here actually uses items in category 2, and who just hoards them?