For some players exploring is tied to finding new gear. I guess it comes down to whether a player is a roleplayer or a powergamer. A powergamer is more likely to do the things you describe. A roleplayer won't. As a roleplayer, knowing where certain items are does not affect my enjoyment of exploring at all. If anything, it increases my enjoyment.
I think what Skooma Addict is trying to say is that, when exploring, there are few surprises in Oblivion. I know personally I loved just knowing that there were hand-placed items all over Vvardenfell. It made each dungeon and building interior feel a little more unique. After all these years I still don't know where a lot of this stuff is hidden (I don't read Wikis or visit the Spoilers forums) - and I love that. If I started a new game of Morrowind tonight I might very well stumble across a piece of gear I've never seen before.
For me, the thrill of discovering a unique, hand-placed object is largely missing in Oblivion. I actually stopped playing the game a few weeks after it was released, partly because I knew that wherever I went and whatever I did I would never, ever, ever see even one single piece of (to take your example) usable glass armor anywhere in the game until my character reached some magic number decided upon by the developers. Once that magic number was reached glass armor was everywhere. That's just poor game design. The 'bandits-In-Daedric-Armor' syndrome has become emblematic of everything that went wrong with Oblivion. Hopefully they will not make that mistake again in Skyrim.
I agree with you about difference between power gamers who first question is "where can I get the best gear" and roleplayers. However on second play trough you know many of the locations and have heard about other, yes you can ignore that location on next play trough but numbers of suitable locations will be limited. Fallout 3 is bad here as you had set of unique items and the bobleheads, Morrowind had multiple sources for most tings.
However Bethesda has to take in account all the fools who go by list of finding the best items and then complains that the game is to easy.
Oblivion's largest problem in my opinion is that every enemy is to close to you in level, Daggerfall was even more random and level scaled, but had a larger variation in enemy level, you had a small risk of running into daedra lords at level 8
your only option would be to run for your life. And yes a lack of hard areas, who had been easy to add to the game, levelled list start at 20.
Much general container loot in Morrowind was actually random level scaled, notable is Ald'ruhn manor district who is nice to loot, however if you wait to higher levels you get lots of exquisite rings and amulets for enchanting.