Man, you still don't get it do you? No one is forcing you to play that way, that's entirely your choice.
No one is forcing me to equip the most powerful weapons I find, to craft the most powerful spells I can craft, to build my character in the most effective way possible (which can mean something ridiculous like picking major skills that you never use, etc.) , but that is part of a role playing game for me. To look at all the variables and enjoy the game as my character grows from insignificant wimp to a legendary hero. Personally, I don't spam spells very much, usually just to get those last few levels to journeyman, but I still believe the mechanic that lets you do that is broken.
If there were an unintended glitch where you could talk to a certain NPC and suddenly get 100000 septims, certainly, we could all just avoid it, and most of us probably would (myself included). But the dev team would acknowledge that that is something broken that needs to be fixed.
I don't play that way in Oblivion, aside from some early Conjuration spamming, and my character doesn't suffer at all from not doing it. Just the opposite in fact. Everytime I play I get bored at about level 15 because I'm just not coming across many enemies that are a match for me, among other things. At that point I pretty much need a 3 to 1 match, with at least one of them being a high level creature, before I really end up breaking a sweat in combat.
I find the entire leveling system has lots of problems in Oblivion and I prefer to play with several overhaul mods that make combat a lot more deadly. (In order to get through almost every battle, I usually die at least a few times and have to reload.) Each playthrough lasts at least 300-400 hours for me.