Omegaslayer, DooM Was awesome and cnahged the world of gaming forever!
Doom3 on the other hand had not only lacking gameplay, contrary to what you said, the level design is actually bad, it repetitive, FAR FAR FAR too dark, the weapon models are very poor, and the only decent looking enemy is the soldier. I mean, just look at doom 3's cacodemon, it farts for gods sake! Doom 3 does not have good level design, and despite what a lot of people might think, it does use a lot of square, or bland rooms, it just overuses Bumbmapping on a grand scale. That and almost none of the original team played any part in making it. The only thing to praise doom 3 for, is its texturing, but Chronicles of riddick has MUCH better textures, lighting and level design, even if it is only 1hour 30 long.
Chronicles of Riddick, escape from butcher bay, has to be one of the best games in a while, the same goes for vampire bloodlines (which uses the source engine) The level design in vampire is not the best ever, but the visuals are stunning, and for Riddick, i hated the film (pitch black was a great film though) but the game was great both visually and gameplay wise, they put so much thought into the level design. Also, mgs2 was not complex, the tanker was amazing, but the rest of the game was poor, lacking in both texture quality, layout design and details. That and the storyline was poo.
As for the actual topic in hand
Yes, I think mapping has changed the way i look at games immensely, i will constantly wander around now and look at things, trying to work out how many units its made up of, and try to pick up tips from the proffesionnals, while at the same time ill see multpiple things wrong with some levels. I done really think its changed my outlook on life much though.
Cheers
PS: if your bored, play Chronicles of Riddick, i enjoyed it, and i hate Riddick. It reminded me of the stalone film, Breakout, or Lockup or somerthing similar. Its a good buy if you see it reduced, and dont play the Xbox one, youll miss out on driving a riot guard 
[addsig]