...hum...that's not a valid point
I have the game, played over 1000 hours of OB and never felt compelled to use invisibility spells because it made the game easy. You say you want the game to be challenging but you can't resist using a spell that you know will make the game less challenging? I'd say it's your fault :shrug:
You think a game mechanic is so badly balanced that you avoid using it completely for the enormous playtime of 1000 hours and then you say leave it as it is? I fear I don't understand your attitude.
Yes, but after reading peoples thoughts I came to the realisation that my memory of Oblivion mechanics was flawed.
As I also posted, wich conveniently you ignored, I much prefer a Morrowind style mechanic where invisibility simply does not work when cast in the line of sight of an NPC. I also like how it dispels with any action.
Furthermore I wrote that I would like to see NPC mages and higer level monsters use detect life and dispel.
As it was in Oblivion one needed master level in illusion to use it effectively, and that is another thing Im happy with.
Its not availble straight out the sewer.
These balancing factors, I agree, are important.
I haven't played Morrowind for a long time, so I can't remember exactly how invisibility worked in MW. Only thing I can remember is that I stole a diamond from a vendor in Balmora using invisibility and thought 'that was lame'. And the diamond was worth a lot for my character back then.
Like I said, if invisibility was implemented well it would be nice. Like actors noticing you are there if you get too close or run around. Since it's an illusion it would only make sense if the spell was completely dispelled in that case, without any dispel spells or detect life spells cast. It's easy to hide from an actor's line of sight, even when in combat (run around the next corner or behind a rock). Activating objects is not needed in most cases and you can simply cast invisibility immediately again. So more obstacles would be needed to balance the spell imo.
EDIT:
This goes a long the same argument as the people who want fast travel taken out of the game because they are to tempted to use it.
Fast travel is about immersion. It doesn't make the game more or less challenging except for the additional time needed to get from location A to location B if you have no fast travel (and MW type transportation instead). Invisibility removes almost all challenge from the game and thus it breaks the game if you use it. It's no glitch or bug either, it's something the game offers you.