As much as I like firearms (own a few myself), this is one idea that I hope never sees the light of day in TES. I could come up with justifications as to why firearms wouldn't be developed in the Elder Scrolls universe, but at the end of the day it all boils down to the fact that I play ES games so that I can cast magic and fell my enemies with medieval weaponry. There is a sense of chivalry in that. Adding guns would, IMO, detract from that feeling. In short, guns - even simplistic ones - would feel out of place in TES. Also, there is the 'slippery slope' to consider. Once you introduce guns into TES, it becomes difficult to revert back to 'ye olden days', and I believe it is a matter of time before we'll end up with a game that is more fable-esque in nature.

I have no intentions of discussing possibilities of technological afvancements etc. which could allow it, but from a setting point of view I am against guns in TES. With passion even.

These firearms threads always confuse me, are you talking about muskets, or later era rifled weapons. Rifled barrels were years and years of gun developement and really can't be considered primitive.
Regular muskets would make no sense there is no way to ever make them accurate they were smooth bore with a round ball ammunition that bounces down the length of the barrel making where it comes out totally random past a very short range and there is no way to overcome it with skill level it's just physics.

If Bethesda ever add any kind of Guns then I will truly hate them... The #1 Reason why I don't play Fable anymore is guns and other Technology!

The only gun-related thing I am okay with would be Hand Cannons! Other then that, Crossbows and Bows!

Crossbows weren't used much outside of Vvardenfell, because of the sheer amount of Dwarven ruins there.
Levitation was banned by the Mages' Guild between Morrowind and Oblivion, because too many people flew too high and fell to their deaths (kind of an in-series joke on Bethesda's part).
Alchemy labs I have no smart-ass like response for, and I think it's horrible that we have to use them...

And of course I do want all of these things back in the series.

Alchemy labs were added for the same reason that repairing was taken out-- because it makes no [censored] sense that I can be standing waist deep in a swamp in the middle of nowhere and actually make a viable potion. You need at least a somewhat controlled environment in order for the product to be even remotely usable.

My only gripe is that the alchemy tables stick out like a sore thumb almost anywhere you put them, because they're really ornate and almost look dwemer in origin.